Can you verify that the add-on is enabled? orange Firefox button ''or'' Tools menu > Add-ons On the left side, click Extensions. Is it enabled? If it's enabled but the button is not on the Add-ons Bar (or anywhere else), it could be in the button palette. To display the palette, you can right-click the Add-on Bar and choose Customize, or use View menu > Toolbars > Customize If you have the orange Firefox button (abbreviated menus), tap the Alt key to display the classic menu bar to get the full View menu.