Try reading How to make the new Firefox look like the old Firefox.

for the moment you still can manually change that behaviour - enter about:config into the firefox location bar (confirm the info message in case it shows up), search for the preference named browser.tabs.onTop & toggle it to false by double-clicking it. however this setting might lose its effect in a future version of the browser, for more information also see www.ghacks.net/2012/07/26/mozilla-tabs-on-bottom-feature-needs-to-go/

thank you!

Current Firefox versions only show the "Tabs on Top" menu entry in the "View > Toolbars" menu and in context menus if the tabs aren't in the default position on top.

If the tabs are on top and the menu entry isn't available and you want to move the tabs below the navigation toolbar then you need to flip the browser.tabs.onTop pref to false on the about:config page like posted above.

Shame on you Mozilla for taking away our ability to EASILY customize our browser like we used to be able to. I always loved Firefox, but you're making me think I will have to go to Google. Wise up!

And Google Chrome even gives you a choice of where the tabstrip is located?

There is also a setting, "browser.tabs.drawInTitlebar". Does that make the tabs appear below the title bar if it is false, rather than covering the title?

The browser.tabs.drawInTitlebar pref applies to having the window size set to "Maximize".
If the window is maximized then on the Windows platform the tab bar appears in the title bar if the Tab bar is on top.
It doesn't have effect when the window isn't maximized because in that case the tab bar isn't in the title bar.

Thank you! going to about: config & making that one change fixed it. I'm all for progress, but I really wish mozilla would stop fixing things that aren't broken and changing locations of things that makes it hard to do simple things like change cookie settings, etc.

Given that this simple screen configuration is causing bother to so many people why is it not a simple "View" option?

It should be EASILY user-configurable.

Why does every version of Firefox get less user-friendly?

There are a lot of people who are unhappy with the idea that having the tabs under the toolbars is eventually going to be impossible. There have been many messages to that effect in the Mozilla newsgroups, so the Mozilla developers are aware that taking the choice away is bothering a lot of people. They are disregarding the opinions of users and are going ahead with their own agenda regardless.

This doesn't make sense.

If I want my tabs at the bottom like I always liked them, always used them, and I really hate to switch things because I reach automatically where things are, I have to invalidate my warranty and type into the code itself?

Seriously?!

Are you expecting me to open the file and type into it?

Tell you what. I'm deleting Firefox after this post and switching to Chrome.

They might not offer me the choice to switch my tabs to the bottom *either*, but they didn't have that option in the beginning and took it away later. It's the principle of things.

One less user. Not much, but think about it. Is it really worth it to "improve" things nobody wants?