Why can I reset the Administrator account, but not another user on same device

Why can I reset the Administrator account, but not another user on same device

Both Administrator and other user have admin rights on Windows desktop.
I am able to change the password for the administrator, but get Access Denied when attempting to change the user account.
Error Occurred - 2147024891 Access is denied.
                New to ADManager Plus?

                  New to ADSelfService Plus?