you mean user at system > users > user list? can you try tmsh command?
root@(B1600-R70-S28)(cfg-sync Standalone)(Active)(/Common)(tmos) create auth user test role admin shell bash prompt-for-password changing password for test new password: confirm password:
Can I assume that you have remote authentication configured? If so, then that is by design. If you need to customize the authorization properties of a given remote user then you would simulate the creation of that account, locally, using the same name.