Did you make the correct modifications to users.php? Something tells me you messed up somewhere there, because everything works fine on my boards...
Try re-tracing your steps and taking out the modifications you've made, and re-doing them.
The administrator permissions are similar, except that with the permissions, the only way to stop another administrator from editing or deleting the "super" administrator is to remove their editing permissions for all users.
Exactly, this allows the admin to edit other members without being able to edit the super admin.
I've gotta create a hack where you can change your username via user cp though, so the admin can change his name whenever he wants.
Nevermind, this feature already exists in MyBB...