You do not share with us HOW you switch screens. Here are several ways you might switch screens properly (if you are not doing it already).
Actually there are five or more acceptable methods shown in the thread.
Why is how you do this important? Because part of your issue might be how you may be misusing real screen use.
Some of the code in individual screens may be using excessive memory. If you share images of some of your code. Developers here may point out possible issues. Sorry, can't do that without you exposing some code. 