Windows Media Player

My question is this.  I unclicked the box and my Sansa Fuze manually syncs (which I do like).  I don’t have to save any playlists, etc., and can add files as I want them.  But the strangest thing now is - how do I go back to automatically syncing (if I want to)?  The box w/the automatically sync is now gone and says this player syncs with another library.  Any help w/this?