When updating adhoc charges it is tricky to make sure i have update each charge with new rate, to have the little filter arrows marking all marked with "yes" to go to top of list. Filter by yes only would be even better, therefore hiding the No adhoc charges not being used.
I'm hitting the same issue, I added a new carton size and it's at the bottom of the list and I have no way to get it with the existing cartons except delete and start again