The ability to lock a shipping price was primarily added so that a zero shipping price can be locked in on a particular order.
Beside the freight field on a quote, order or invoice, is a lock button.
Clicking it will lock the freight amount so that it cannot be changed from anywhere in Paradigm or DeliverMe unless it is unlocked.
In order to unlock the freight field, click on the lock button again.
Note: When the freight field is locked, there will be no way to make changes from DeliverMe.