Boot up the game and then at the main menu:
Click the Options button -> Global login profile -> Edit profile. Now all you need to do is delete what ever is in both of the windows and put the your account name and then type the name you wish to use (if you have more then one linked to your account in DPlogin. Now click the [Set to Name] button and then click okay. Now just retype your password and you are all set.
That is about as descriptive as I can be so I hope it helps.
If that was not enough, although it may sound stupid, but are you sure you have a global login account?
If you do, check
this topic for some extra information.