Hi @thomastees ,
When you are logged in as an Admin, you can change the Usergroups of any member. But if you log - in as the "Registered Member", then by default, they should not be able to change their usergroup, from their own profile, unless a setting was changed on what they can and cannot do.
There are settings that you can check, when logged in as an Admin:
More Info here:
Good luck and God bless you! 🙂