That hasn't been an option in Firefox since the Firefox 29 version was released!

I suspect that you were using an add-on that 'restored' the old 'tabs on bottom' feature; and now that add-on is disabled. Check your Add-ons Manager > Extensions tab to see if you have a "not verified" message.

How soon we forget! You're right, I was using the Tabs on Bottom extension. About:addons showed it was still enabled but it wasn't working. I installed the Tabs on Bottom (Australis) extension and that works!

Thanks for your quick response!

Great, just great, someone tells us what works but doesn't give us the HOW or WHERE to get this autralis thing!!!!!!

Does anyone know where to find it??????????????????????????

Note that you can also achieve this without using an extension with code in userChrome.css.

Add code to the userChrome.css file below the default @namespace line.

• http://kb.mozillazine.org/userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* tabs on bottom */
#navigator-toolbox toolbar:not(#nav-bar):not(#toolbar-menubar) {-moz-box-ordinal-group:10}
#TabsToolbar {-moz-box-ordinal-group:1000!important}

The customization files userChrome.css (user interface) and userContent.css (websites) are located in the chrome folder in the Firefox profile folder.

• http://kb.mozillazine.org/Editing_configuration

• create the chrome folder (lowercase) in the <xxxxxxxx>.default profile folder if this folder doesn't exist
• use a plain text editor like Notepad to create a (new) userChrome.css file in the chrome folder (file name is case sensitive)
• paste the code in the userChrome.css file in the editor window
• make sure that the userChrome.css file starts with the default @namespace line
• Make sure that you select "All files" and not "Text files" when you save the file via "Save file as" in the text editor as userChrome.css.
  otherwise Windows may add a hidden .txt file extension and you end up with a not working userChrome.css.txt file

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

• Classic Theme Restorer: https://addons.mozilla.org/firefox/addon/classicthemerestorer/
• Tabs on Bottom (Australis): https://addons.mozilla.org/firefox/addon/fdgueux-tabs-on-bottom/