For the moment, down payment were used with the basic revenue account for product, but that created problems in the accounting, as down payments were considered as revenue when they should actually be considered as payments in advance, and the revenue should be recognized when the invoice is made. 

If I put a different account, I'm not sure the invoice lines will be well compensated when the invoice is made. 

Also, for the moment a down payment invoice is in the same journal as all the other invoices and there is no way to recognize easily whether it is a normal or a down payment invoice. 

How can I change this ?