For example, when Data was moved to first officer under Captain Jellico in "Chain of Command," he switched to the red/maroon uniform. But when he was placed in command of the Excalibur in "Redemption," he stays in gold.
Jellico is on record in the episode as "liking a certain formality on the bridge." Therefore, I always thought that Data should have switched to the red uniform in "Redemption." It seems to be the "formal," or correct, thing to do.