In production view in Consignor, you have an area at the bottom called COD. To send a shipment with COD, you must enter the amount as indicated in the picture below. Notice that it will only work if the carrier supports COP shipments.
The COD account will only change automatically on the receiver address when you select another country. If the new country does not exist in the COD Setup Item, the last value will be used.
If COD Account is missing see FAQ: How to add a COD account