...
Also, if for some reason you do not want to not store history of a Secure Fields at all for a certain field, you can set it up, by going to:
Issues → Fields → Custom fields
picking the cog wheel by the Secure Field you do not want, then pressing
Configure → Edit Permission scheme → unchecking the box Save field history and clicking Done.
And there you go, history for this field will not be kept any longer.