Go to View menu -> Show/Hide > Connections -> then in that window select your UP listed as connected & at bottom press Remove button. Wait for it to connect to another UP. Then remove the others one by one that were originally listed. Perhaps removing just one or two will do the job.
Different UP's will give different search results because they themselves are connected to different peers & different 'other' ultrapeers. Keep in mind the maximum horizon of a search on gnutella network is limited; http://www.gnutellaforums.com/genera...ally-work.html & also http://www.gnutellaforums.com/limewi...tml#post332858 & related links within.