How can I fix zoom controls to specific screens / locations?

I do a lot of online teaching (on Mac/OSX).  Typically using Powerpoint/Zoom and BetterDisplay to set up a dummy third screen.

The Zoom controls often move from one screen to another.  They can end up hidden behind other windows.

I want to set it so Zoom controls stay in one place, and are never hidden behind other windows.

(the issue is independent of whether I use BetterDisplay - which solves powerpoint issues on OSX).