I have a Humminbird 525 fish finder and would like to know if it is possible to have the back light on without the light/contrast screen staying on in the middle of the screen. I fish at night a lot and of course need the back light on but the whole time I have it on the setting screen for the light brightness and contrast stays on. I find nothing in the manual telling me if or how this can be turned off so just the light is on. Thanks for any help.