"Tuning" Raymarine DS500X for better interpretation

[Peltz]

I have a Raymarine DS500X. It is a decent unit and holds bottom at all speeds and shows great detail. I have a problem interpreting the detail. It is hard to tell the difference b/n fish and bait. They both show up as red blobs. I see red blobs a lot and when I think it is bait it is often fish and when I think it is fish it is often bait. I mostly fish in the Chesapeake in less than 40 feet and leave it on automatic Fishing mode most of the time. I am hoping to learn how to "tune" the unit to be better able to decipher information on the screen. Any advice? Thanks