Where did the preferences / settings go in Firefox? I used to go to the menu bar and under "Firefox" is preferences option. I would post the version of Firefox I'm using but I don't know it is because the "About" menu item is also missing from the Firefox menu too!
Using "about:" as suggested, I was able to find that the version is 35.0.8. I'm also using a Mac.
I found a button in the lower right hand corner on the Firefox home page. It is still missing from the Firefox title bar menu items which is really what I'm looking for in this question.
I found a button in the upper right corner on new blank web pages. I've added an screenshot.
I found an icon you can add to the tool bar. You can see it here:
You have to click customize and then drag the settings icon to the tool bar.