Actually, Ste will forward it to me. So, you might as well PM me with the request.
If a person requests a username change, I usually do it since this is what they are "living with". If it becomes a habit of a person wanting multiple changes or I'm inundated with requests, then it might not be honored.
If the username is inappropriate, it will be changed if already registered, or it won't be allowed if requested. Everyone should be able to use some common sense with that.
If you want a change, please PM me with the exact username that you want and why you want it changed.