Hi @stacy_kissel,
If you're using the term question banks, that would usually means you're working with Classic Quizzes. In that quiz system, the banks are more owned by a course than a an individual user, so anyone else added in to your course shells could modify the banks. In New Quizzes, Item Banks are generally owned by a user and then (optionally) shared with a course. Administrators will generally be able to see anything they wish, but I believe other teachers would be restricted to whatever is in their courses (for classic quizzes) or has been explicitly shared with them or a course they teach (for New Quizzes). I don't yet have a ton of New Quizzes experience, so if I'm wrong about this, I'm sure someone will come in and correct me soon.
-Chris