Did you (a) uninstall the Norton free-trialware AND THEN (b) download/run the Norton Removal Tool & reboot (c) BEFORE you installed a replacement application (e.g., the Bullguard application) AND BEFORE you upgraded the Win7 computer to Win8?
So your answer to the very specific, three-part question in my previous reply would be NO, is that correct?
Firefox [v29.0 is installed]
Chrome [v65.61.49249 is installed]
If all were well with your computer (it's not!), Firefox would have auto-updated itself to v38.0.5 (released 02 Jun-15) or v39.0 (02 Jul-15) by now - and Chrome would have auto-updated to v43.0.2357.130 (22 Jun-15) by now. [Google changed the version-naming convention several years ago so I have no idea where or how you got v65.x.]
That being said, were Firefox & Chrome already installed before you upgraded to Win8?
Thank you re warning Flash Player plug in. I shall upgrade immediately
Good luck. In Windows 8.1, Flash Player is kept up-to-date via Windows Update. See http://technet.microsoft.com/en-us/security/advisory/2755801 as well as https://helpx.adobe.com/flash-player/kb/flash-player-issues-windows-8.html