uniform switch

[Robsladey]

Ensigns with a red uniform could simply indicate they are training at the helm. When Dr Crusher becomes a Captain in the alternate timeline does she wear red because I can't remember?

[Kuro-chan]

Yes. She transferred to command, although I can't any reason why a blue uniform can't have the rank of captain. In the US army, there are doctors who can carry the rank of Colonel, right?

[Robsladey]

Although if you're a doctor and become a Captain your duties would change dramatically. You wouldn't be working in sickbay you'd have too many other duties so I suppose you would have to wear red and really put your doctor work aside.