Normally you don't need to set the closing force, but if the trunk cannot close all the way, then you might need to increase the closing force. To do that, use a flathead screwdriver to push up the lock in the latch to virtually close the trunk, then hold the black button on the back of the control unit. One beep means force 1, two beep means force 2 etc. Release the button when you hear your desired force. The default force is 1.