Hi,
I think someone had a similar problem to which I posted a reply.
http://forum.x-cart.com/viewtopic.php?t=17218&highlight=
I have not heard back, so am not sure how they got on. However, I am guessing that it is not working properly as there are more files involved. I imagine as you are editing what is essentially a form, you are only changing a fraction of it. You would need to edit the php as well that works the form.
My solution is a work around that allows you to use the User Profiles options under General Settings.
Let me know if this gets you moving in the right direction.
Paul Dodman
e-business consultant
Lumino Internet
luminointernet.co.uk