Don't push the button all the way down. There is a slight "middle" detent that you're overriding with your heavy touch.
Just press lightly until you start the window going down, and hold it there/release it at the desired window position. This is not easily accomplished if the car is bucking about on a rough road...
Slightly-related rant and possble thread hijack: My Autodown
doesn't work at
all now. [Underbreath cursing]. Yes, I know how to reset it. I've reset it, repeatedly, and no joy. Hey! Trade you switches!