In Some times, Exit from app is not Working when click on back navigation. Blocks are provided below.
always switch screens correctly
There is no issue when closing a screen. Only problem when close application function
read this for better understanding why switching screens also affects closing the app
App Inventor Tutorials and Examples: Manager Screen | Pura Vida Apps
protip: therefore switch screens correctly to be able to close the app
How set it if we opens screen with a value?