I've assigned a new hair of a mod to a NPC, but it is not persistent. I save the mod in the CK, but when I reloaded it, the hair comes back to the default set of hair. also in game.

What happens?

Please, REPOND TO MY QUERY!!!!!! YOU KNOW ABOUT MY PROBLEM!!!! WHY IGNORE ME???

A user with a similar problem:
When I create a NPC, I just make sure that plug-in .esp or master is checked in the data menu but not the active file. The active file is your mod.
I then create my NPC, and the hair plug-in will be available as a choice for hair.

I specify in my release notes for that esp that the hair pack I used is mandatory, or the NPC will appear bald (unless it was a replacer, in which case it will just appear differently).

Thais is not my problem. What could it happen?