When I installed an addons, I don't see it in the overflow menu or anywhere in the toolbar. When I entered the Customize Toolbar page, I only saw my other addons, but my new addon is nowhere in sight, making it useless. I have seen lots of solution to this, but they doesn't work for me. I'm running the latest update of Firefox and my Firefox is not set to Automatic Private Browsing. Please help!

Thanks in advance.