If you want to change the password of ATT mail and know the current password you should try the instruction those are described here.
1. Sign in your ATT mail account.
2. Now click on settings of the mail.
3. Click on reset AT&T password link.
4. Now create a new password and then re-enter to confirm it.
1. Sign in your ATT mail account.
2. Now click on settings of the mail.
3. Click on reset AT&T password link.
4. Now create a new password and then re-enter to confirm it.
Visit here:
recover AT&T password