Firefox 32-bit doesn't "update" to the 64-bit version. You have two separate versions of Firefox 43.0.3 installed, which may be a good idea considering the Win 64-bit version only supports the Flash and Silverlight Plugins. If you need Java or any other Plugins for Firefox you can switch to the 32-bit installation. Overall, the NPAPI Plugin system is being phased out within the next year or so; this limitation with Win 64-bit Firefox is one of the first steps in that phase-out. In the not too distant future web browsers won't need Plugins, HTML5 Audio / Video and other "standards" will handle what Plugins are now needed for.