Sounds like you're referring to the update notification alert, not an 'install manager'. If so, you can modify your update options in the Flash Player Settings Manager: System Preferences > Flash Player > Updates tab. The Updates tab also displays the version installed. The current version is 18.104.22.168. If you're getting update notifications you most likely don't have the latest version installed (either the NPAPI plugin for Safari/Firefox, or the PPAPI plugin for Opera and Chromium-based browsers).