Payment methods are labels that record how a client made a payment – for example, Bank transfer, Bitcoin, or USDT. They are used when logging top-ups, so you can track the payment channel for each transaction.
Go to Settings → Config → Library → Payment methods.
Click Create:

In the window that opens:

In the Name field, enter the name of the payment method (e.g. Bank transfer, Bitcoin, USDT).
Click Create.
Once created, the method appears in the Payment methods list with a status of Active and becomes available as an option when recording a client payment.