There is a problem with the button to clear download history in Firefox 19 and a bug report has been filed. See the following for information and workaround solutions: *https://support.mozilla.org/en-US/questions/951103 *https://support.mozilla.org/en-US/questions/950875 Big changes are coming in the download panel in the next release, Firefox 20. New download interface and apparently list will clear after restart, but you can clear download history from the Library (''CTRL+SHIFT+H'') window as Downloads are now considered part of History. You can always set Download History to clear when closing Firefox in the options ''Firefox button > Options > Options (or Tools > Options) > Privacy > [x] Clear history when Firefox closes > Settings''. *See - http://techdows.com/2013/02/disable-firefox-panel-based-download-manager.html *See (previous report when first released in Firefox 14) - http://techdows.com/2012/06/hands-on-firefoxs-new-downloads-panel.html