FAQ #: 18
I changed the cost of an item on the Purchase Order, but it did not change it in inventory.
The Last Cost and Next Cost of the item in inventory will not be updated with the new cost until the Purchase Order is received in through Stock Receipts at the new cost. At this time (provided the Update Cost option is enabled on the P/O), the Last and Next Cost will be updated on the inventory item. This assumes your system is configured to updated Last and Next Costs automatically upon receipt. Average, FIFO, and/or LIFO Costs are also always updated in Stock Receipts.