If the sign-in doesn’t work, then you need to debug these blocks:
I have a method I use which I explain here.
I would, for example, start by assigning a label’s text to the “Email” and “Password” properties and see what is displayed when you re-open the app. Are they blank or do they have values? If they have values, are they the same values you typed in before?
If they are what you expect, then what error are you getting? You can assign the green error block to a label or text input (if you want to be able to copy it and paste it here).