I have AOS disabled in Firefox, and the icon doesn't appear at all. It definitely looks like he has AOS enabled.
Since the last firefox update that changed the interface to a quasi chrome interface, it messed up lots of things, no add-on bar, etc. Now I have made some changes (other add-on) to be able to get that back; I find that you may have to go to the firefox customise function to find the AOS icon and drag that back to where it should be.
I don't know if that will work for kenny556 or not.
I haven't been using the AOS for some time now, so I can't really offer much help outside of trying to get the icon back.