I can't sign in to my personal Gmail Account
You can be signed in to only one Google Account at a time in the same browser. If you're signed in to your DoubleClick product in one browser (such as Internet Explorer), you can sign in to your personal Gmail Account in another browser (such as Firefox or Chrome).
You should avoid using a personal Gmail Account when updating your sign-in information. We encourage you to use your work email address (firstname.lastname@example.org). If you don't have a Google Account that uses this address, we recommend you create one.
If you accidentally used a personal Gmail Account to update your sign-in information, learn more about how to undo the update.