Additional settings-related features and issues within Microsoft Teams for business
Here is how this is solved. The Admin goes logs in to Microsoft 365 and goes to the Admin portal using the black button on the left with all the other apps. Then you go to Teams & Groups. Then Active teams & groups. Click on the name of the Team. A window will open. Go to Members. Then "View all and Manage Owners" Add new owner. Delete old owner.
Jim Tupitza