Restoring closed toolbars

Sometimes I close the upper toolbars in the Acrobat reader in order to maximize the document part of the window. When I do that, however, I often regret it: I cannot find a way to restore the closed toolbars. I expect to see the little black toolbar at the bottom, in which there is a tool for shrinking back the page, but it doesn't always show. And I couldn't figure out the riddle of what makes it show. (A really friendly UI have Adobe geniuses devised for us---for genius users only.)