You can have multiple payment methods. This makes it easier as you can take cheque or cash on site, or if you use credit card integration then you can take card payments onsite too.
In order to add a new payment method, go to your system settings and from the 'Invoicing' section, click 'Payment methods'.
You will see a form on the left-hand side and a list of existing payment methods on the right-hand side. You can add your new payment method on the left and it will appear on the right when you click 'Add payment method'.
Click 'Edit' next to any payment method you wish to change. You will see a page where you can edit the information with a space to name the payment method. Change this information as required and click 'Save payment method'.
Simply click, drag, and drop the payment methods to reorder them. If you want to move a payment method from page 2 to the top of the list, then change the number of payment methods showing per page to 10 or more (depending on how many payment methods you have). You can also delete them from here, using the button on the right.