Sorry all for taking so long to upload again. At first I stressed the videos, then I got too relaxed. I'm trying to find a happy medium so that everyone can be happy. Thank you all for your constant support!
To listen while using other apps, switch the player to Picture-in-Picture (PiP) during playback — it keeps playing in a small floating window (the screen stays on).
To listen with the screen fully off, in-browser playback stops by YouTube's design. Open the video in the YouTube app to keep listening where background playback is supported (e.g. with YouTube Premium).
Open in YouTube app