The current method of changing your account's default "from" address is very confusing and misleading. First, you click "My Account" and then "User Email." Finally, you get to this screen:
The problem here is that I am the user. I have my own email address. It is the one I log in with. It is the one I want you to send invoices and reports to. My coworker is a user. She has an email address. It is the one she logs in with and has reports sent to. That, to me, and I imagine many others, is what you would call a "User Address."
So, when I see "Change User Email Address," I'm not quite sure what I'm doing. Am I telling you that I, personally, have a new email address? Because that's what it seems like.
Nowhere on that page does it inform me that the action I am about to take will change the default "from" address on my account. And nothing in the navigation that led me to this page was intuitive at all. I pretty much just clicked around on everything that said email address--and still contacted support because I was unsure of what I was doing when I reached this page.
SOLUTION: I believe this function belongs in the My Settings section (which should be called Account Settings because they are account/organization-related, not user-specific) under Email Message Settings alongside the From Name.