Orders close automatically depending on the OrderClosingMethod setting. You can view this parameter in CORE > Setup > System > Settings > Parameters. Do not change this setting without careful planning. The meaning of the values are below:
If not defined, the setting behaves as if the value is 0.
0 – Close order after it has been fully invoiced. For manufacturing orders, closes after fully shipped.
1 – Close order after it has been fully shipped.
2 – Close order only after it has been fully invoiced and fully shipped. If an order can only be invoiced (credit if the company doesn’t ship credits, invoice only), it closes when fully invoiced. If an order can only be shipped (manufacturing), it closes when fully shipped. If an order can be invoiced and shipped (order, credit if the company ships credit orders), it closes when fully invoiced and fully shipped.
Orders can also be closed manually through the Order Maintenance screen.