I did my 1st OS upgrade to the new V30 firmware, previously running V26 I think on my Mk IV DVD Nav unit. However, i'm unable to change the brightness of the screen permanently. I can adjust it via the 'Set' menu option along with split screen, time, date etc, but the next time i start the car teh brightness has been reset to default again, and is too dim. Any ideas why? Is there a way i can set this to be at max brightness permanently or do i have to set it each time i start the car.

Any help appreciated.