That is why I always uninstall older version first. You have no choice select what will be installed during program update. Unistalling previous version first is also better for compatibility. New program version come with new uninstaller so you will not be able uninstall remains from previous version. For example update from v.12 to 17. There will be no way uninstall Avast Screensaver by this new uninstaller, although if you uninstall v12. first, screensaver is deleted. There is also utility called Avastclear, which should delete everyting but i never tested it.