Big-up to the hardcore Burd Squad Y'all rock my little burdy socks :) x Also, please let me know which questions you'd like me to answer. I'm thinking of doing a Q&A :-)
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