Supplier Update Ledger

Hi, I have noticed that when updating supplier ledgers for part invoices I am not able to go back and update ledgers for remaining items on the invoice, when viewing the update ledger screens it shows that the items have already been invoiced when I know they haven't.

Is there a setting somewhere which controls this behaviour?

I am using version 2014 sage 50 accounts pro version 20.04.09.364

Kind Regards Paul