Firefox may restore a previous session if that is set to do that on the Options page, or if Firefox believes that it needs to recover from a crash, or if the tab was left open when Windows shut down. (That third one is a "new in Firefox 62" feature: [[Firefox starts automatically when I restart Windows]].) Do any of those seem possible? ---- Regarding most visited sites, were those the tiles on the new tab page, or was it a menu item? One reason you might have a different new tab page is if an add-on has taken it over. You can check on the Options page: * Windows: "3-bar" menu button (or Tools menu) > Options * Mac: "3-bar" menu button (or Firefox menu) > Preferences * Linux: "3-bar" menu button (or Edit menu) > Preferences * Any system: type or paste '''about:preferences''' into the address bar and press Enter/Return to load it In the left column, click '''Home''' Then on the right side, you can whether New tab page is set to "Firefox Home (Default)" or "Blank Page", and if Firefox says an add-on is controlling the page. Any progress so far?