Need some advice... trailer brake adjustment...

I've been using the same non-Prodigy for 20 years and it has 2 user adjustments. I'd suggest you download the manual for the one you have (if you don't already have it)and set it up according to the manual and then fine tune it for your personal preferences. I'm thinking that if it already feels jerky your trailer brakes are probably working fine and simple adjustments will get the job done. Personally, I like to feel when the trailer brakes apply; just don't want to lock 'em up on a normal stop.