depend on how you make those changes...if you have the email generating the username, then when the change is made it would create a new account - this depend son how you provision your users.
You can make a change manually; even to the username without affecting any previous records. That said, even if you have a new account created, the previous records would still be intact on the old profile so you could merge those profiles into the new one...lots of manual work though unless you explore using APIs.
Thank you for your reply. I would be making the change as an Admin directly in the system through the account “edit” feature (there are only a handful of users that need this change). So it sounds like changing the username and email address through the admin interface will not change the course record. Correct?