Do you mean you had it set for your homepage and now it's not? (when you would bring up google chrome the log in page for your email would be the first thing you would see?) If so, Follow the steps in the following screenshots to make it your homepage. (you may have to click on the pictures individually to enlarge them)
By the way, I deleted your email from the original post.
NEVER post your email address in a public place unless you want it overrun with spam and thousands of unwanted emails.
First bring up the AT&T mail sign in page (
LINK HERE)
(#1) Go to the upper right in your google chrome where the 3 lines are click that. There is a drop down box (#2) click on settings
Select set pages
Copy and paste the AT&T homepage link into the popup box
Was this what you meant by your question? You needed to change your homepage in google chrome?