If you are wanting to switch accounts so that the secondary account holder becomes the primary account holder and vice versa, all you have to do is cut and paste the names, emails, and phone numbers into the new account holder fields. Be sure to click "save" after changing the account information.
If you are changing account holder information in two different accounts, this can be a little more tricky. The system will not save an account with the same email address as another account. You can add a "+1" or another term after a plus sign to save the account. Then go back and take it out after saving.