I have been looking and Googling and looking some more and while I have found some snippets of documentation that sort of talk about this topic...there is nothing that sets things out in a crystal clear fashion so...I am asking.
It is my understanding (please correct me if I am wrong) that the Guest and Account terminology on the Foxy Checkout page has absolutely not one thing to do with PayPal Guest and Account anything. My client (whose store uses Foxy) has been under the impression for a long time that the Guest and Account under the email address had everything to do with PayPal and was quite surprised to hear from me that it had nothing to do with PayPal (suggestion: you may want to clarify that somewhere in your documentation as it even had me confused for a while).
It is also my understanding (and again please correct me were that is wrong) that a Guest checkout is one and the same as checking out without saving any of the info entered into the Foxy Checkout page.
That an Account checkout is one and the same as saving the info entered into the Foxy Checkout page for future use by the customer.
Now to my (and my client's) question....
How does a customer update their saved Foxy Account information?
My guess is that they simply checkout as an Account holder and that whatever information had previously been saved by Foxy for that account is overwritten by any new information entered this time around. But...my client tried to change an address that way and could not save his changed info in that manner.
Some of your documentation says...
If the cart parameter is set to updateinfo, the cart will immediately redirect to the checkout in “updateinfo” mode. Simply put, this will process an empty transaction, thus allowing the customer to update their password, address(es), or payment info. This updated information will be sent in a transaction datafeed, but the payment gateway will not be contacted during this checkout. (https://wiki.foxycart.com/v/0.7.2/checkout
...which implies that updating is a factor of how the Cart is called.
The store uses version 0.7.2.
Any input on this would be appreciated.