Nav/Stereo Head Unit Problem

[dinkeye]

Everytime I turn on my car, I get a diiferent screen on the dispay. If I am listening to Sat radio when I turn off the car, when I turn it on it might be on the nav screen, then the next time I turn it on I get the air/heat cotrols. Why wouldn't it come back on with Sat radio where I left it. I've just been ignoring it, but it is getting annoying! Any thoughts?