Hello,
Since app can't be saved, you will need to save the quiz data into the .mat file, and load it next time the app is opened.
If there's only one user who runs the app on his pc, you can create .mat file with the quiz data, when the user clicks close button (https://www.mathworks.com/help/matlab/ref/matlab.ui.figureappd-properties.html#mw_298b0342-aa53-4f7d-a2f3-79a3451fb0a4 - CloseRequestFcn), and on startup, check if file exists, load it and fill the data.