^ What he said.
It sounds like you're fairly new to Star Trek; if you watch the original series at some point as well as TNG, you'll note the command and engineering colours are swapped round between the two series. Rumour has it that the reason is that Data's makeup tested better with yellow than red, so they switched the colours around. Not sure if that's true or just something I heard once.
If that is true, I have disagree with the producers. I always thought Data looked better in the red uniform. Maybe it's just that I'm so used to seeing him in the gold that the change is nice.