Hi @JohnBlair,
I do believe the bookmarked banks still live in the course where they originated. For example, if you bookmarked a bank in a Fall 2017 course, but are using it in a Fall 2024 course, the bank is still residing in Fall 2017. This isn't necessarily right or wrong, just multiple ways you could work with this. At my institution, our courses go into read-only mode at the end of each term, so while banks from old term courses could work, they couldn't be edited anymore.
What our faculty do is import content from one course to the next, which should create a new copy of the question bank associated with the new course, where you'll be able to edit things to your lining (and also not affect your old, completed course). This is just one approach to this problem, but it may help you out here. You definitely should not have to retype any questions!
-Chris