I thought about it for a sec, but I'm guessing (and this is purely a guess on my part) that my username is unique and a key field in the SQL database that is the back end for NAT.

Changing "NVDave" to "WYDave" and keeping my profile and linkage to all the posts I've made would likely require some SQL manipulation of the database directly, and I'm reasonably sure that Ed, DG, dko, Gary and others have many, many better things to do with their time than get wrapped around fat-fingering the SQL database just for me. So I'm content to remain as "NV" unless there's some clamor for me to change...