Who can see the question banks I make?
Banks are shared in the Question Bank Library. Tick Keep this bank private to keep one out. Anyone with a bank's share link can still see it.
Banks are shared in the Question Bank Library so other teachers can use them, the same way you can borrow theirs.
To keep a bank out of the Library, tick Keep this bank private (just for me) on the Bank Settings step. Leave its share link off if you do not want other teachers to see it.