In Firefox 87+ the Library and the Home button aren't present by default on the Navigation Toolbar and you need to drag them out of the Customize palette to the toolbar. *https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars Do you mean the Bookmarks Menu button that shows the bookmarks in a drop-down list ? You can drag this button as well from the Customize palette to the Navigation Toolbar. See "How do I add the Bookmarks Menu button to the toolbar?" *https://support.mozilla.org/en-US/kb/bookmarks-firefox