You can update the email address and other account details registered to your SQUARE ENIX Account by following the steps below:

(1)  Log in to the SQUARE ENIX Account Management System.
(2)  Under ‘Account’, select ‘Account Information’. You may be required to enter your registered Date of Birth.
(3)  Select ‘Update Account Information’.
(4)  Select the account details you wish to change: ‘Update detailed information’, Update password’,‘Update e-mail address’, ‘Update security question and answer’, or ‘Cancel SQUARE ENIX Account’.

NOTE: Once your SQUARE ENIX account is created, you cannot update your SQUARE ENIX ID, first/last name, date of birth, and country/region.

* If you are unable to log into the SQUARE ENIX Account Management System, confirm your SQUARE ENIX ID and reset your password if necessary. If you require assistance with recovering your account, contact the SQUARE ENIX Support Center through the ‘Additional Assistance’ option located at the bottom of this article.

For more information regarding login issues, see here.