You can learn how to change your default account.A lot of us have more than one account.You can assign or change your account.
Step 1: Go to http://mail.google.com in your browser.
Step 2: Click on your picture.
It can be found in the top right corner of the mail screen.You should be able to see a list of the accounts associated with your computer.
Step 3: Sign out of all your accounts.
To open the account page in a new window, click on another account from the drop down menu under your profile picture.Click on your profile picture in the new window to sign out.You should repeat this process for all of your accounts.
Step 4: If you want to make your default account, you need to sign in.
You can sign in to your account at www.accounts.google.com/servicelogin.Only after other accounts have been signed out can you do this.You have to log into your account.Next to this account in the account list, you should see '(default)'.If you don't see it yet, refresh the page.
Step 5: You need to sign in to other accounts.
Just make sure you log in to any other accounts you've created.