I'm not sure exactly where your tabs are, but generally speaking, Firefox can place them either above or below the address bar, always above the web page content. To get them on the left side typically would require an extension. If you have one named Tab Utilities on the following screen -- orange Firefox button (or Tools menu) > Add-ons > Extensions category -- check out this thread: [https://support.mozilla.org/en-US/questions/953933 My tabs are on the side... how to get them back to normal?] If that's not it, could you possibly post a screenshot showing where they are? This article has tips on how to capture one: [[How do I create a screenshot of my problem?]]

Can you attach a screenshot? *http://en.wikipedia.org/wiki/Screenshot *https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem Use a compressed image type like PNG or JPG to save the screenshot.