Purchase orders can only be edited if no items have been received from the purchase order. If any items have been received, the corresponding purchase/receipt must be removed before the purchase order can be edited. In this case, the purchase order should be closed. See Closing a Purchase Order. Closing a purchase order will remove all remaining 'quantity on order' quantities from inventory.
When a purchase order is saves, the journal entry is re-posted to the database and the quantity on order values are readjusted. This action will not affect the income statement or balance sheet since a purchase order represents an allocation of inventory and not an actual purchase (monetary transaction).
Entering a new vendor
Editing a vendor account
Deleting a vendor account
Setting vendor payment terms and credit limits
Entering a purchase order
Deleting a purchase order
Closing a purchase order
Checking purchase order status (Purchase Order Manager)
Receiving inventory from a purchase order
Receiving inventory directly from a vendor
Generating a request for quote (RFQ)
Writing a check to a vendor
Issuing a vendor credit memo
Checking vendor balances
Setting up tax authorities
Setting up tax rates
Setting up the shipping estimator