The answer
After signing in, open account settings. You can edit the available profile fields and request changes to your password or account email. Security-sensitive changes require your current password.
A new account email must be verified. Editing customer details does not automatically change the registered domain holder. Support reviews those changes separately for existing domains.
What to do
Sign in and open account settings.
Edit the relevant section and save the details.
Complete verification when changing the email address.