Thanks for the information, I did locate, About robotic libraries information which it states:

"Rather than targeting a backup job to a specific group of slots with a finite number of media, Backup Exec accesses all of the media in the robotic library and uses media that belongs to the job’s targeted media set. If the backup job exceeds the capacity of one piece of media, Backup Exec searches all media contained in the robotic library, finds a suitable media, and uses it for the job."

I had well over enough space in media set 2 that it should not have grabbed from media set 1 then converted to media set 2 when finished.  I was looking for a way that maybe I could lock the media sets and never allow that to occur.

I move the media into the set I would like but its during the backup process where the backup should only go to media set 2 and 3 but I find that it will sometimes grab a tape in media set 1 then use that tape and when finished the tape that was listed as media set 1 is now listed as media set 2. 

Thanks for your response, Over write scratch media is selected