How to sign into Google Drive on a computer or phone, and what to do if you can't remember your login information

You can sign into Google Drive using the same username and password as Gmail, YouTube, and all other Google apps.

How to change your Gmail display name without changing your email address

You might want to change your Gmail name but keep your original email address. Here's how to do it through your settings.
Houston Chronicle

How Do You Change Your Primary Username on Gmail.com?

The primary username in Gmail is the username you choose when you create a new email account. If you create a Gmail account through Google + under an alternate email address, such as a Yahoo or ...