To edit and/or add a shipping address: click the account icon at the top of any page and sign in. Click the "View Addresses" link on the right side of the page to see and/or edit all past shipping addresses.
To change your password: click the "Forgot your password?" link on the sign in page. You will receive an email (usually within just a few minutes) that has a link for resetting your password.
To change other account details (like your email address or name): email us at email@example.com.