i am trying to update to new firefox version but only shows on list as a download; doesn't change from old version

I clicked on the green update box on Firefox homepage to update to the new version. The download occurred but it did not install. I shut down and restarted and it's still the old version. I looked at the help screen, and The Open File Security Warning dialog box does not appear for me so I cannot click Run to install. Help?!?! ops, never mind. I clicked on the downdload and the box came up am running now...