Accounts Receivable default

[newby17]

We are having the weirdest thing happening! We have two different A/R account numbers, one for domestic and one for international. We have our customers set up with the proper default account number, but lately we have been having some of the invoices coding to the other account number (i.e., not the default). It goes both ways...some domestic sales are going to international and some international to domestic. There doesn't seem to be any rhyme or reason as to which customers it happens on. Anyone have this happen before? Any ideas for a fix?

Thanks for your help!