@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
toolbar#toolbar-menubar toolbarbutton .toolbarbutton-text {
  display:inline !important;
  padding-left:0.25em;
}

Many parts of the Firefox interface are configurable with style rules. The two ways to apply style rules to the UI are (1) the userChrome.css file and (2) the Stylish add-on. Since Stylish makes tweaking and previewing easy, I'll describe that method. (1) Install Stylish and restart Firefox. https://addons.mozilla.org/en-US/firefox/addon/stylish/ (2) Make sure your icon is on the menu bar. (3) Look for the "S" icon on the Add-ons bar (press Ctrl+/ to display the bar if necessary). Click the icon and choose Write new style > Blank style... (4) Copy the following and paste it into the new rule on the blank line between the curly braces, then click Preview to confirm that it reveals the text for the icon: <br>@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul); toolbar#toolbar-menubar toolbarbutton .toolbarbutton-text { display:inline !important; padding-left:0.25em; } (5) Assuming it worked, go ahead and give your rule a name, such as Show Label on Menu Bar Stylish has many other uses, since it can modify web pages as well as Firefox's "chrome" (toolbars, menus, etc.). Any luck?

Try this extension: *toolbarmode: https://addons.mozilla.org/firefox/addon/toolbarmode/

Thanks jscher2000 and cor-el. I have gone with the stylish addon and its worked.