Well, we can’t for most cases. Because we can’t change campaign presets in customization. We can only change outfits for campaign preset that we had set up before the “customization lock for unique soldiers” came in action.
For example, I can change outfits only in Berlin preset. I can’t even open stalingrad and Moscow presets.
And this problem is only with new Halloween squads, all other squads still can still change presets.