In the Expense function on Quickbooks there is a Drop down feature so you can choose the Payment Account you used to pay the expense. How does one ADD an account to it?

Hello STLtd, 

Welcome to the Community page, 

If you click on plus new>expense>click on the payment account>you should see the very top 1st option is to add new> click that> a pop-up box will appear for you to fill out and save then you will be able to select that new account payment type.