Change role of user in course

Once someone is added as a student in a course, it is no longer possible to add them as TA or staff member. There is also no way for them to leave the course nor for you to kick them out of the course, so a database edit is required.

Instead, it should be possible to "promote" a student to TA or even teacher (this should be default behavior when adding a staff member).

This issue is from my memory, but the first step would be to confirm whether this behavior is still the case.