Registered user name and password

I have a WD MyBookLive and seem only to be connected as a guest.  I can’t connect as the registered user even when I try all the passwords I can ever remember.

How can I reset the log in details?


Just to be specific this is when I try to change from guest to registered user in the Finder on my MacBookAir.

It asks me to Enter your name and password for the server “MyBookLive”.

I have exactly same issue - any answers out there?