Study the manual. You need to figure out for yourself how it works. If you don't, you will get things out of proper adjustment and get really frustrated wondering why they don't work right. It's takes a little getting used to, but you have to know how to access the menu and get to the right adjustment. Just play with it, watch what the servos do when you adjust, then reset them to their neutral point. When you get used to how everything works, and what it means, you can adjust your brakes on the fly without giving it a second thought. I have 2 computer radios, on for the MT, and one for the heli and planes. You have to get used to the settings. Once it's set correctly for what you are using it for, you rarely have to change anything.
The manual is crap for the mx-3... Epa stands for end point adjustment Trim is where is you are going down the street and you notice it going left then you would trim it to the right... sub trim is the same as trim but finer