i am thinking of gettin a 4pls what does happens when you push the default dual rate ,steering trim ,throttle trim buttons beginner here please be gentle

i know what everything means but do not what happens when u push the buttons

When you press the buttons either way its adjust the servos. For example if your car is pulling to the right, you adjust the steering trim so that it steers straight. Basically the trim fine tunes the servo position.