because you don't have a seperate decals folder that that other skin. If 2 units have differing numbers, and assuming decals are randomized (only Level=2, btw), you'll need a different folder for ANYTHING the other squadron uses. Also assuming there's at least 1 Level=1 decal to activate the squadron name display, and said "squadron specific" decals
Switching to another squadron via the mission editor should not remove things like national markings or "service names", (again) assuming those are all Level=0)
If, OTH, you used something like
Navy
VAQ-111
that, being squadron specific, become a Level=1 decal, as it names the squadron