To create a new Payment Type, go to File --> Company Information and Settings. On the Company Information Window, click the A/R & Showroom link. Next, click the Add button to the right of the Cash Receipt Payment Types grid. Enter in a new Type designation for the Payment Type and select the desired Checking Account from the Checking Account menu.
Click OK to save. You can also use the 'up' and 'down' arrows to move the new Payment Type towards the beginning or end of the Payment Type list.
When adding a new Asset (Bank/Checking) Account, you should be asked to create a Payment Type which would streamline the process in the future.