MoveBoardA long-distance order has a pickup and a delivery, each with its own trucks. Settings › Dispatch › Delivery truck auto-assignment saves you picking the same truck twice. When it applies, and when it can't, is in Delivery truck auto-assignment.
Before you start
Anyone who can open Settings can change this page. Never set means No.
The switch
Under Assign the pickup truck to delivery automatically: On a long distance order, should selecting a pickup truck also assign the same truck to the delivery leg? — No / Yes.
Press Save.
What happens next
With Yes, adding a truck to a long-distance order's pickup — on the order's truck schedule or the dispatch board — also puts it on the delivery for the delivery dates. Taking a truck off the pickup doesn't take it off the delivery.