Default Payment. Terms on Imported Invoices

Default Payment. Terms on Imported Invoices

I am importing invoices using data from our production software.  I do not import payment terms.

I noticed that when the invoice is created, it does not use the default Payment Terms defined in the Customer record.  It creates the invoice with "Due upon receipt".  How do we change this.  We generate a bunch of invoices and do not have time to go into each record and edit them individually.

Thanks