''thishearth [[#question-1156657|said]]'' <blockquote> When I download an add-on it'll download perfectly but when I double-click or right click it to install it does nothing, no prompt or window. </blockquote> Mozilla add-ons from addons.mozilla.org (such as [https://addons.mozilla.org/en-US/firefox/addon/reminderfox/ this example]) have an "Add to Firefox" button that doesn't require you to save a file to your computer. What type of installer file are you downloading? Please post a link to one of the download pages that links to the add-on you are trying to install.