When installing Windows apps you should be cautious about what you agree to when you’re installing it. More and more apps are now trying to sneak in extra stuff like a toolbar or an extension that can be installed in your default browser (or every single browser you’ve got installed on your system), resulting in the browser behaving erratically. The extra stuff either changes the default search engine, injects ads, and can even manipulate search results. Chrome deals with it by alerting you when an extension is trying to make changes to your browser’s settings and asks you if you want to allow the extension to do so. Firefox is in the process of introducing something similar. As of Firefox version 40, you can check if an installed add-on is ‘unsigned’ and with the Untrusted Add-on Switcher add-on for Firefox, you can enable/disable all unsigned extensions with one click.
Install Untrusted Add-on Switcher and it will add a golden add-on icon to the address bar. Click it to disable all unsigned add-ons. The add-on’s icon will change to a golden add-on icon with a red cross on it. For some add-ons to be disabled, you might have to restart Firefox.
An unsigned add-on will originate from outside the Firefox add-on market. Add-ons hosted by Firefox are all created and signed by registered developers and Firefox reviews them to make sure they are safe. As of version 40, the browser now differentiates between signed and unsigned add-ons on the about:addons page. With version 43, all unsigned add-ons will be disabled by default but until it rolls out, you can use Untrusted Add-on Switcher to toggle their active state.