You to make sure that you understand how such a smart folder list works:

• "Most Visited" and "Recently Bookmarked" and "Recent Tags" are examples of so called Smart Bookmarks folders and are not real existing folders.
• Smart folders show a list created by a query of the places.sqlite database that stores bookmarks and history in Firefox.
• Smart folder lists show a maximum of 10 entries by default.
• Bookmarks and history items that show up in a smart folder list are stored elsewhere in another folder and any changes made are applied to the real bookmark or history item.
• If you remove an entry then the list is shifted up and a new entry that wasn't shown previously is added to show 10 entries.
• Actions like copy & paste or delete that you perform on bookmarks in such a list are done on the original bookmark.

There a good chance that items on the Recently Bookmarked list are physically stored at the end of the Unsorted Bookmarks list. To move those onto the Bookmarks menu or Bookmarks toolbar, you may find it convenient to use the Library dialog, which you can open using either:

• Ctrl+Shift+b
• "Show All Bookmarks"

Click Unsorted Bookmarks at the lower left, and then you can drag items from the right side to the Bookmarks Menu or Bookmarks Toolbar, as you prefer.

In the future, if you double-click the star Firefox will show a dialog immediately to let you move it right then. Or if you use one of these methods to add the bookmark, the default location starts off as the menu instead of unsorted:

• Ctrl+d
• right-click the page > star icon