zoom window closes when I select another window on remote monitor

I am running zoom v 5.13.6 on Mac OS Big Sur - 11.7.3.  on a laptop.   after launching zoom and joining a meeting,  I move the zoom meeting window to my remote monitor I can view it ok.  When I select another app window on the monitor , the Zoom meeting window closes, and I can only open it by selecting the zoom app icon on my laptop from the tool bar.   HOW do I keep the meeting window open on my remote monitor.  ( behind another window is fine, but closed is a problem.  

other people on. my team don't have this problem, so it must be something in my settings. ?    Any help is appreciated.