To change a payment method we must access to:

Finance → Payment Management → Payments List.

Once we have entered, we will see the list of collections that have been made.

In the list we will locate the payment that we want to change the form of payment and we will press the icon .
When we have clicked we will see a window like the following:

As we see, from here we can change a payment method of payment, whether in cash, card, balance or transfer. 

When we have changed the type press Update and this charge will have been modified.