How to change your User details and Password:

1.) Click on the button on the left column of this page marked: "Password Details"
2.) Fill in the required details, then go down the page to the password details.
3.) Click on "Save Changes"

How to change your Billing or Mailing Address:
1.) Click on the button on the left column of this page marked: "Addresses"
2.) Click on the "Add" or "Edit" link beside the address you want to change/edit/add.
3.) Enter your details then click on "Save Changes"