You might find that you’ve downloaded an add-on program or feature in Firefox that you may not want anymore. Sometimes, they can end up changing fonts or features in your browser that can be especially annoying.
To get rid of add-ons, click on “Firefox” in the top-left hand corner of the screen. There, press on “Add-ons”, which will take you to the add-ons manager.
Then, click on the “extensions” tab, which will list every extension and add-on. There, click on disable, and then remove, to get rid of the add-ons.
Your browser will need to restart, but then you’ll be done.