You can
update any details you like, contact information, User ID and password.
You can change your default credit card, or enter a card if you didn't
do so at registration.
To update your details, simply make the changes you want and click the
Submit Changes button at the bottom of the page. When your details
have been successfully updated, you will immediately go on to a screen
displaying the message "Thank you, your details have been updated".
If you do not see this screen then your update has not been successful
(a message will be displayed and any incorrect fields will be highlighted).