Почему не работает qsettings?

Я написал код и хочу чтобы он сохранял изменения, но этого не происходит и я не знаю почему.

Помогите, объясните что не так плииз!!!

Вот код:

import contextlib
from PyQt5 import QtCore, QtGui, QtWidgets


from food import Ui_MainWindow

class SettingsManager:
    def __init__(self, filename):
        self.m_settings = QtCore.QSettings(filename, QtCore.QSettings.IniFormat)

    @property
    def settings(self):
        return self.m_settings

    def read(self, widget):
        self.settings.beginGroup(widget.objectName())
        if isinstance(widget, QtWidgets.QAbstractItemView):
            selectionMode = self.settings.value(
                "selectionMode", type=QtWidgets.QAbstractItemView.SelectionMode
            )
            widget.setSelectionMode(selectionMode)

        if isinstance(widget, QtWidgets.QTableWidget):
            rowCount = self.settings.value("rowCount", type=int)
            columnCount = self.settings.value("columnCount", type=int)
            widget.setRowCount(rowCount)
            widget.setColumnCount(columnCount)
            items = self.settings.value("items")
            if items is None:
                self.read_defaults(widget)
            else:
                stream = QtCore.QDataStream(items, QtCore.QIODevice.ReadOnly)
                while not stream.atEnd():
                    it = QtWidgets.QTableWidgetItem()
                    i = stream.readInt()
                    j = stream.readInt()
                    stream >> it
                    widget.setItem(i, j, it)
                selecteditems = self.settings.value("selecteditems")
                stream = QtCore.QDataStream(
                    selecteditems, QtCore.QIODevice.ReadOnly
                )
                while not stream.atEnd():
                    i = stream.readInt()
                    j = stream.readInt()
                    it = widget.item(i, j)
                    if it is not None:
                        it.setSelected(True)
        self.settings.endGroup()

    def write(self, widget):
        self.settings.beginGroup(widget.objectName())
        if isinstance(widget, QtWidgets.QAbstractItemView):
            self.settings.setValue("selectionMode", widget.selectionMode())

        if isinstance(widget, QtWidgets.QTableWidget):
            self.settings.setValue("rowCount", widget.rowCount())
            self.settings.setValue("columnCount", widget.columnCount())
            items = QtCore.QByteArray()
            stream = QtCore.QDataStream(items, QtCore.QIODevice.WriteOnly)
            for i in range(widget.rowCount()):
                for j in range(widget.columnCount()):
                    it = widget.item(i, j)
                    if it is not None:
                        stream.writeInt(i)
                        stream.writeInt(j)
                        stream << it
            self.settings.setValue("items", items)
            selecteditems = QtCore.QByteArray()
            stream = QtCore.QDataStream(
                selecteditems, QtCore.QIODevice.WriteOnly
            )
            for it in widget.selectedItems():
                # print(it.row(), it.column())
                stream.writeInt(it.row())
                stream.writeInt(it.column())
            self.settings.setValue("selecteditems", selecteditems)
        self.settings.endGroup()

    def release(self):
        self.m_settings.sync()

    def read_defaults(self, widget):
        if  widget.objectName() == "tableWidget":
            widget.setSelectionMode(QtWidgets.QAbstractItemView.MultiSelection)
            widget.setRowCount(1)
            widget.setColumnCount(4)
            for i in range(widget.rowCount()):
                for j in range(widget.columnCount()):
                    it = QtWidgets.QTableWidgetItem("{}-{}".format(i, j))
                    widget.setItem(i, j, it)


@contextlib.contextmanager
def settingsContext(filename):
    manager = SettingsManager(filename)
    try:
        yield manager
    finally:
        manager.release()

class MyWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, rows):
        super(MyWindow, self).__init__()

        self.rows = rows
        self.setupUi(self)

        self.pushButton.clicked.connect(self.set_row_count)
        self.tableWidget.cellChanged.connect(self.cell_changed)

        self.tableWidget_2.cellChanged.connect(self.cell_changed_2)

    @QtCore.pyqtSlot()
    def set_row_count(self):
#        self.rows += 1        
#        self.tableWidget.setRowCount(self.rows)
        rowPosition = self.tableWidget.rowCount()
        self.tableWidget.insertRow(rowPosition)

    def cell_changed(self, row, column):
        _sum = 0
        if column == 2:            
            if self.tableWidget.item(row, column) != None:
                try:
                    _sum +=  int(self.tableWidget.item(row, column).text())
                except:
                    pass

            _bud = 0
            if self.tableWidget.item(row, 1) != None:
                try:
                    _bud = int(self.tableWidget.item(row, 1).text())
                except:
                    pass    
            ost = _bud - _sum            
            self.tableWidget.setItem(row, 3, QtWidgets.QTableWidgetItem(str(ost)))



    def cell_changed_2(self, row, column):
        _sum = 0
        if 0 < column < 6:
            for column in range(1, 5):
                if self.tableWidget_2.item(row, column) != None:
                    try:
                        _sum +=  int(self.tableWidget_2.item(row, column).text())
                    except:
                        pass

            _lgota = 0

            if self.tableWidget_2.item(row, 5) != None :
                try:
                    _lgota = int(self.tableWidget_2.item(row, 5).text())
                except:
                    pass

            ost = _sum - _lgota

            self.tableWidget_2.setItem(row, 6, QtWidgets.QTableWidgetItem(str(ost)))
            self.tableWidget.setItem(row, 2, QtWidgets.QTableWidgetItem(str(ost)))

    def closeEvent(self, event):
        self.write_settings()
        super().closeEvent(event)

    def read_settings(self):
        with settingsContext("data_T_W.ini") as m:
            for children in self.findChildren(QtWidgets.QWidget):
                if children.objectName():
                    m.read(children)

    def write_settings(self):
        with settingsContext("data_T_W.ini") as m:
            for children in self.findChildren(QtWidgets.QWidget):
                if children.objectName():
                    m.write(children)

if __name__ == '__main__':
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = MyWindow()
    w.resize(751, 551)
    w.show()
    sys.exit(app.exec_())

food:

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'food.ui'
#
# Created by: PyQt5 UI code generator 5.10.1
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(746, 608)
        MainWindow.setStyleSheet("QLabel {\n"
"    font-size:14px;\n"
"}\n"
"\n"
"QPushButton:hover{\n"
"    background-color:silver;\n"
"}\n"
"\n"
"QWidget {\n"
"    background-color:white;\n"
"}")
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tabWidget = QtWidgets.QTabWidget(self.centralwidget)
        self.tabWidget.setGeometry(QtCore.QRect(10, 30, 731, 531))
        self.tabWidget.setObjectName("tabWidget")
        self.tab = QtWidgets.QWidget()
        self.tab.setObjectName("tab")
        self.dateEdit = QtWidgets.QDateEdit(self.tab)
        self.dateEdit.setGeometry(QtCore.QRect(860, 20, 110, 22))
        self.dateEdit.setObjectName("dateEdit")
        self.pushButton = QtWidgets.QPushButton(self.tab)
        self.pushButton.setGeometry(QtCore.QRect(0, 0, 111, 41))
        self.pushButton.setStyleSheet("QPushButton{\n"
"    background-color:gray;\n"
"}\n"
"\n"
"QPushButton:hover{\n"
"    background-color:silver;\n"
"}\n"
"\n"
"QPushButton:pressed{\n"
"    background-color:white;\n"
"}")
        self.pushButton.setObjectName("pushButton")
        self.tableWidget = QtWidgets.QTableWidget(self.tab)
        self.tableWidget.setGeometry(QtCore.QRect(10, 50, 431, 431))
        self.tableWidget.setStyleSheet("")
        self.tableWidget.setObjectName("tableWidget")
        self.tableWidget.setColumnCount(4)
        self.tableWidget.setRowCount(1)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget.setVerticalHeaderItem(0, item)
        item = QtWidgets.QTableWidgetItem()
        item.setText("Имя ученика")
        self.tableWidget.setHorizontalHeaderItem(0, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget.setHorizontalHeaderItem(1, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget.setHorizontalHeaderItem(2, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget.setHorizontalHeaderItem(3, item)
        self.tabWidget.addTab(self.tab, "")
        self.tab_2 = QtWidgets.QWidget()
        self.tab_2.setObjectName("tab_2")
        self.tableWidget_2 = QtWidgets.QTableWidget(self.tab_2)
        self.tableWidget_2.setGeometry(QtCore.QRect(0, 10, 721, 521))
        self.tableWidget_2.setObjectName("tableWidget_2")
        self.tableWidget_2.setColumnCount(7)
        self.tableWidget_2.setRowCount(1)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setVerticalHeaderItem(0, item)
        item = QtWidgets.QTableWidgetItem()
        item.setText("Имя ученика")
        self.tableWidget_2.setHorizontalHeaderItem(0, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setHorizontalHeaderItem(1, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setHorizontalHeaderItem(2, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setHorizontalHeaderItem(3, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setHorizontalHeaderItem(4, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setHorizontalHeaderItem(5, item)
        item = QtWidgets.QTableWidgetItem()
        self.tableWidget_2.setHorizontalHeaderItem(6, item)
        self.tabWidget.addTab(self.tab_2, "")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 746, 22))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Добавить ученика"))
        item = self.tableWidget.verticalHeaderItem(0)
        item.setText(_translate("MainWindow", "1"))
        item = self.tableWidget.horizontalHeaderItem(1)
        item.setText(_translate("MainWindow", "Бюджет"))
        item = self.tableWidget.horizontalHeaderItem(2)
        item.setText(_translate("MainWindow", "Потрачено"))
        item = self.tableWidget.horizontalHeaderItem(3)
        item.setText(_translate("MainWindow", " Остаток"))
        self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab), _translate("MainWindow", "Бюджет"))
        item = self.tableWidget_2.verticalHeaderItem(0)
        item.setText(_translate("MainWindow", "1"))
        item = self.tableWidget_2.horizontalHeaderItem(1)
        item.setText(_translate("MainWindow", "Хлеб"))
        item = self.tableWidget_2.horizontalHeaderItem(2)
        item.setText(_translate("MainWindow", "Булочка"))
        item = self.tableWidget_2.horizontalHeaderItem(3)
        item.setText(_translate("MainWindow", "Горячее"))
        item = self.tableWidget_2.horizontalHeaderItem(4)
        item.setText(_translate("MainWindow", "Напиток"))
        item = self.tableWidget_2.horizontalHeaderItem(5)
        item.setText(_translate("MainWindow", "Льгота"))
        item = self.tableWidget_2.horizontalHeaderItem(6)
        item.setText(_translate("MainWindow", "Сумма"))
        self.tabWidget.setTabText(self.tabWidget.indexOf(self.tab_2), _translate("MainWindow", "Питание"))