You have a misunderstanding.

Itch has 2 ways of working.

"Collected by itch.io" They charge users and save the money and then you, manually, request Itch to pay you the money that corresponds to you (deducting taxes, the itch part, card commission, etc.).

In this model, you must complete the tax interview and must manually request payment from Itch.

If you have already sold even a single game under this model, to recover that money, you must request manual payment to Itch, you have no other way to claim that money.

The second model, "Direct to you", is a way where you become responsible for charging users directly, Itch stops being an intermediary, and therefore Itch is not the entity that charges, nor is it the entity that will pay you, if not, that each customer who buys your game is paying you directly, through the options that you have selected and configured.

As you can see, they are totally different models.

If you change the payment method, the change is NOT retroactive, because basically the client paid Itch instead of you. As I mentioned above, if someone bought your game and paid Itch, it doesn't matter what method you have at this moment, as they paid Itch, you must manually request payment from Itch.

PS: In "direct to you", you are responsible for paying taxes such as VAT.