Now, to fully understand my problem I have to tell you that my parents own an Android tablet (which one is irrelevant). After not being able to sign into Google Play with my main Google account (which has the email address at yahoo.com), I made a new Gmail account from the respective tablet, so they could sign in to Google Play and download apps.
After that, somehow, my main Google account (Yahoo address) and their new Gmail account got tied together. Naturally, I didn't want that, so I deleted the new Gmail address from my main Google account. The problem is thou, that now Google won’t let me make a new Gmail address (on my main Google account) with a username that is different from the one that I deleted.
Also, at dashboard, under the 'Account' tab is listed my Yahoo email address and username, which was used to make the Gmail account on the tablet.
So basically I'm stuck with a username that I do not want and cannot change. If anyone has any ideas how to change it or how to add Gmail with a different username that would be great.