[support] Trying to access/edit "user/login" form as Admin, but locked out: "You are not authorized to access this page."

I've installed module(formdefaults). Formdefaults' instructions say: "Navigate to the form you wish to modify ..." Once logged in as Admin, works nicely on any/all forms, except ... I'd like to edit my "user/login" form using it. @ nav to "user/login", & I get: "You are not authorized to access this page." How can I be "not authorized" ? I'm Admin ... Any help with this Catch22? How do I access/edit the "user/login" form? Thanks, BenDJ