Hi, you seem to be using Firefox 57, and in that version all old (Legacy) add-ons are disabled. The new standard for add-ons will be WebExtensions, so you need to find something compatible with your version of FF. This one is being transitioned to WebExtensions so may work https://addons.mozilla.org/en-US/firefox/addon/new-tab-tools/ ''If your question is resolved by this or another answer, please take a minute to let us know. Thank you!''