2.0.3.1 Prices in placed orders change

Client places order - prices on the Order confirmation are as expected.
Administrator changes price of a product - that new price is then applied to the previously placed order and is what the admin now sees online as due from customer.
Unfortunately - the order confirmation is what the customer is due to pay - not the amount now shown outstanding for the order. After shipping the Shipping confirmation also shows the new (current??) price.