What 'bar at the top?' Do you mean the Bookmarks Toolbar? [https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars Customize Firefox controls, buttons and toolbars] {web link} Type '''about:customizing'''<enter> in the address bar. Note: '''about:customizing''' is no longer present in Firefox v47+ releases. * Press '''Alt''' or '''F10''' to bring up the Menu Bar. Then '''View > Toolbars > Customize.''' * Right-click on a blank spot in the toolbar and select '''Customize. ''' Look for '''Show / Hide Toolbars''' or just '''Toolbars''' at the bottom left. There is also a '''Restore Defaults''' button at the bottom right.

See also: *https://support.mozilla.org/en-US/kb/bookmarks-toolbar-display-favorite-websites