In order to use national, fleet, lease type of accounts or perform third party invoicing you need to link the given customer to the account that you want to invoice.
- Go to POS
- Click on the spy glass right next to customer
- Choose the customer that you want to invoice to third party
- On the "Customer Information" tab you will find the field "Invoice this customer"
- You need to click on the spy glass next to the field "Invoice this customer" and choose third party account
- Click on the green clock
- Click on save
NOTE: If the third party account is not in your system you need to create it beforehand. (How to create new customer)