You don't control what the query does, you can change the query, you might prefer 20 hits instead. Searching from the location bar with the "AwesomeBar" feature might be more to your liking. In any case do not remove the entries in "Most visited" as you would delete actual history

Most Visited -- Smart Bookmark Folders -- recently visited (History list)

https://support.mozilla.com/questions/831554

https://support.mozilla.com/questions/858163#answer-225990

After creating the bookmark for a "smart folder" you must, restart Firefox after which the bookmark looks like a folder and will function properly.

related: https://support.mozilla.com/kb/Smart%20Bookmarks%20folders (marked old)

related: http://kb.mozillazine.org/Viewing_the_browsing_history_-_Firefox

AwesomeBar feature allows you to search your history and bookmarks from the location bar until (before) you press "Enter". See Location Bar search (internal - Auto Complete)

see picture for some about:config settings I use related to AwsomeBar feature internal search.

Thanks for your help dmcritchie. I set up a new Smart folder following instructions you provided and that will meet my requirements perfectly!

I would like to disable this feature totally. I use several tabs and when deleting the tabs the feature leaves 2 to 3 blank ones behind each tab I remove making the removal of sometimes 25 tabs take too long as I have to wait for the blank ones to disappear before removing the next in line. It is very frustrating. Please help. I tried to find a way to control it but on my Mac OS X there is no such choices. If you are wondering why so many tabs, I have many accts. and copy and paste the same forms for each acct. Thank you for your quick response, much appreciated.