Magic Mouse scrolling works for one user account, not the other

MacBook Pro 2020, running Monterey (12.6.2). If I log in as "user a" I can scroll easily with one finger. If I log in as "user b" the same mouse ignores scrolling. As "user b" I can only scroll by use of the scroll bars (click and drag). Same mouse, same Mac, same OS - user login is the only difference.

Other gestures on the mouse surface do not work as well when logged in as "user b", though they do when logged in as "user a".

I compared the system preferences > mouse for both users and they seem to be identical. But something must be different someplace.

So then I created a new user "test user" and logged in. Scrolling works!

Right now only "user b" cannot scroll using the Magic Mouse surface. I don't want to delete/create "user b" as there are many files, etc. within that user's directory already.

Any ideas where to look to fix "user b's" problem?

Thanks,

Gary