In the system, the Handbook "Payment Methods" contains all possible ways in which the client pays for services, they can also be called invoices and cash desks. In this case, the corresponding fields indicate the main cash desk, or the method of payment, which is cash.
To change the value of any field in the required record, you need to hover over it, press the right mouse button and select the «Edit». Or simply double-click on this entry to open edit mode.
With the «main» checkbox, you need to cancel the payment method that customers use most often, so that the program will substitute it automatically. There should be only one such check mark per table.