The "Exit" is under the red Firefox button in the upper left corner, almost the same position as the File menu was in. You can get back your Menu toolbar and other things that you may miss from 3.6.17. If the purpose of closing Firefox is to quickly restart it again, I would suggest installing the "[https://addons.mozilla.org/firefox/addon/restartless-restart/ Restartless Restart]" extension. It adds an item to the File menu but I prefer to use the keyboard shortcut ("Ctrl+Alt+R") that it also provides. You can make Firefox 4.0.1 look like Firefox 3.6.17, see numbered items 1-10 in the following topic [http://dmcritchie.mvps.org/firefox/firefox-problems.htm#fx4interface Fix Firefox 4.0 toolbar user interface, problems (Make Firefox 4.0 look like 3.6)]