HankLloydRight
No Roads
what button to push to get the screen I want when I want it (want rear to see if I'm in enough and front to see if I'm in too far - both screens active while driving forward).
There are no buttons to push each time. If installed correctly, it will automatically show the rear camera only when reversing and then the front camera when going forward. If you want to change that, you can press one button on the included remote, or program one of the homelink channels to do the switch between front and rear.
Also, there's no "both screens".. it's just one screen that switches between front and rear views.