How do you change work clothes?

I can't figure this out for the life of me. I can sometimes get the Sim ID but only when in play mode. I can't get the IDs once Cas is open. Once I have the ID I have tried in Cas, play mode and via the manage households route to put in the full code (the code plus the ID) and nothing happens, no option to modify the work outfits. Can someone explain in more elementary terms, maybe with pictures? I understand how to cheat, how to modify in Cas and I can do this on random townies for all outfits except work attire and whatever random crap they wear at festivals but this seems to be much more sensitive and particular.