How can I force my app users to be signed in whenever they have to do something on the app?
I have a form that they have to fill out every morning and on submit I retrieve with ‘‘values from user profile’’ their Site/Project in order to filter the info shown on the screen. The thing is some of them, for some reason, they get logged out and they are too lazy to log in again and when they fill out the form I can’t retrieve their Site/Project.
It’s any way to have a column with a value for the ones that are logged in? based on that to hide or show different buttons or pages. Thank you!

Is there a reason why you make sign in optional?
If you force your users to sign in, then you won’t have this problem.
Yes, the reason is that I need people who do not have an account to have access to some limited info . For example I have some NFC tags and QR codes across the Project that each shows a certain page in the app, visible to everybody, users or not.
Okay, understood.
What you can do in that case is set a visibility condition on the form (or whatever opens it) such that it is only available to signed in users.
The way to do that is as below:

thank you very much, Darren. I appreciated