How to make (Android) phone app stop

It seems stupidly simple, but I cannot find a way to shut down the Android app (Volumio 3). At the end of the day, I “close” the app by going to my home screen and turn off my Pi3. The next time I pick up the phone, there is Volumio - almost like a screen saver. Touching the fingerprint reader makes it go away and brings up my home screen, but is there any way to just make the app STOP and go away until next time I want it?
Possibly relevant info: Current Volumio3 version, Pi3, Motorola g pure, Android 11.

||| on you bottom of your phone select the app you want to close and slide up with the app

I don’t know about your phone, but on mine that is not possible. The very bottom has triangle (back one page) a circle (home page) and a square (recent apps) Above that are 4 “permanent” apps that appear on all pages (user selected). Nowhere does it show active apps such that you could swipe up as you describe.

If you click on this, you can scroll through the open apps. If you swipe one of these apps (up, down. left or roght) it will close the app.

https://www.verizon.com/support/knowledge-base-239649/

Yup. That works At least sliding up works. Thanks
Interestingly shutting down the app has no effect on the Pi playing the current playlist.

Correct, the app is to control Volumio. If you load a playlist, closing the app will not clear the list within Volumio. If you want this you need to do this from the app first.