When I use the app on my phone I am unable to switch screens

So I created an app that has more than one screen. When I use the app viewer thingy on my phone I cannot switch screens. Is there a code or something I should be putting to switch screens?

http://www.appinventor.org/content/howDoYou/screens/swap

The example that shows opening Screen1 earlier in this thread causes problems with memory depletion.

See FAQ Section: Screens

I'm also having the same problem.
And if someone knows how to import a variable from one screen to another screen without deleting that variable from the first screen with value same

Use the Open another screen with start value block

Another method of passing variables from one screen to another is through TinyDB.
https://groups.google.com/g/mitappinventortest/c/q7DtXwAVucA/m/2ANiB4UmBQAJ

TinyDB and List:

What do you mean?