Hello mweber, This is very common issue, Please visit the given link

Hi mweber100, are you referring to the little triangle-like "Show History" button in the address bar? Yes, that was removed in Firefox 75. Many users changed a setting that undid the redesign in Firefox 75-76. Come Firefox 77, that undo is no longer available. To call up the classic list, you can type a space in the address bar. Can you get used to that? If you want a mouse-only option, I created an add-on which displays a very similar list, but it has to use a separate drop-down because there's no way to integrate it into the address bar drop-down. You can can check out the features and limitations if you're interested: https://addons.mozilla.org/firefox/addon/show-history-top-sites-button/