How to make sure that applications are not thrown out of RAM?

Question

Android

Hello, how can I make sure that applications are not deleted from RAM? The screenshots show the locks above the application windows, these are those that do not fly out of the RAM. By standard, all applications have them, but when you click on this lock, it disappears and does not appear again. How to return it?

Answer 1

This is a feature of a specific launcher for its memory release function. I couldn't identify it from the screenshot. miui?