You are free to change any content on the site at any time, however it is advised that you do not make changes to a course’s assessment if users have already completed it. Doing so may interfere with a user’s results.
If you modify an assessment, make sure to inform your assigned users of the changes and have them re-attempt the course and assessment if needed.
Any changes made to Documents, News, Courses, etc. will automatically be applied to all users who have been granted access to them. There is no need to re-assign modified content.