If you want to make changes to your GSN.com account (account info, player profile, username, password, email preferences, etc.) you must do so via My Account:
Click the My GSN tab:
Then click the My Account tab:
Make any changes you wish and then click the applicable Save button to save the changes.
At this time, the ability to update or change your billing/payment preferences will need to be updated through the Purchase Tokens page.