Portfolio Entries left and right navigation arrow

Hi, i have some problem with the automatic previews’s and before’s arrow in all my portfolio entries.
Even if i consider these arrows very useful and nice i have notice that is impossible disable it or modify some kind of option about it. My problem is that i use portfolio to make many things of my site… for example a monthly music playlist so i can extrat all the playlists with a Grid Portfolio …or… I create single page of sponsor’s so i can extract and place it in Grid Portfolio like the Playlists.
My problem is simple… when i see some kind of sponsor i found in the previews’s and before’s arrow the Playlists too … and it seams there is no solution.

Can you help me?
Thanks