The items in the first section (Top Sites or Shortcuts) can hang around for a long time, but entries in the Highlights section cycle out pretty quickly, within 1-2 weeks. For steps to pin an item in the Shortcuts, see: [[Customize items on your Firefox New Tab page]]. Does that work on yours? If the item cannot be added back because you removed it using Dismiss, you might need to flush the list of dismissed sites (because I don't see a convenient way to edit it). If no one has a more convenient suggestion, here's how you do that: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. (2) In the search box in the page, type or paste '''browser.newtabpage.blocked''' and pause while the list is filtered (3) Click the garbage can icon at the right end of the row to delete the dismissed shortcut list More info on about:config: [[Configuration Editor for Firefox]].