You cannot edit the generated set directly, but you can certainly edit the automatically-generated dashboard action that comes from 'Use as Filter'. From the menu Dashboard >> Actions... you should see an action named something like "Filter 1 (generated)". Edit that filter and choose which sheets you wish to target, as well as which fields should be involved in setting the filter criteria. To change the fields in play, change the "Target Filters" setting at the bottom from "All Fields" to "Selected Fields", and manually define which pairs of source / target fields should be involved in filtering.
I hope this helps,
Wow that worked perfectly. I thought it would be a pain to add all the filters manually but its really easy and quick. THank you very much Robert, you are the man.