Yes - Question Banks can be switched out on Assessments in order to update the questions as needed.
Please Note: If an Admin wishes to change/switch the Question Banks on an assessment that a Learner has started but not completed, this will cause the results to be broken as the Learner's answers will no longer correspond to any exams in progress.
As a workaround it is possible to utilize the Lesson-level Reset Lesson Activity, as seen below.
This will reset the User's progress, and force them to begin the Exam again. Reset Lesson Activity is not an action that can be performed in bulk, so it must be completed on a User-by-User basis.
As an alternative workaround, Admins can duplicate the Online Course, make changes to the Assessment prior to making it available to Learners, and then enroll Users into the Online Course once it is updated as needed. This will allow Admins to make modifications to the Assessment, and retain all User progress data as well.