When you do the upper left corner/ btm left corner hack to get into the override function on the destination....... what does the clock link to in that screen?

Maybe I am just thinking about it wrong, but I adjust the clock normally...without having to go into the hack,
but then I can go tinto the hack, change the time on that screen, but it doesn't actually change the clock I view in the car. What is that clock for? WHat is it linked to?