The way I adjust mine is so that I feel the trailer pull down the truck on light break pedal. If you have to much it will almost feel like the truck is being jerked back and to less it feels like the trailer is pushing the truck forward. You want the trailer to do more of the breaking then the truck. For highway driving (speeds above 50 mph) I normally have my break control set at around 6 (I think mine goes to a high of 12) and for stop and go towing I might turn it back to around 5 or less. I'm hoping that in the future I can get a new Proportional brake controller, been wanting one for years but can't see spending the money when the one I have works fine. With these type of controllers you set it and forget it for the most part.