Downgrade to version 77. FireFox removed this feature completely in version 78 in favor of ad-supported links.

Hi deviant73, do you mean the automatic list that opens when you click the address bar, before you start typing any text?

In a regular window, Firefox may open a list of your first 8 Top Sites from the Firefox Home / new tab page automatically when you click the address bar (unless you've disabled it). In a private window, it doesn't open automatically, you need to press the down arrow key.

However, in either case, if you are looking for the classic frequently visited URLs list, it is simplest to type a space. I'm not aware of any purely mouse-able method for it.