Problem turning off Centre Stage when using Zoom on iMac mini with Studio Display

I've been searching for a solution to this problem and none of the previous Community Advice worked. I had both an unhelpful online chat and an unhelpful call with Apple Support. I finally stumbled across the solution and here is how I fixed the problem:

1. Opened the Zoom App on my iMac
2. Opened Zoom Settings, clicked on General, ticked the box for "Add Zoom to macOS menu bar"
3. Started a Zoom Meeting and exited Full Screen mode.
4. A camera icon appeared on my macOS menu bar at the top of my screen to the left of the word "zoom"
5. Clicked on the camera icon and the drop-down options included Centre Stage icon.
6. Clicked on this to turn Centre Stage off/on

All done!

I hope that helps someone else