How do I change the payouts account number?

Make a transfer from the new account (the so-called verification transfer) to the following account:

Recipient: PayPro SA
Address: ul. Pastelowa 8, 60-198 Poznań
Account No.: 67 1140 1010 0000 5402 7000 1006
Amount: 1.50 PLN Title: ZMIANA XXXXX
Where XXXXX is your User no. (Account ID = Merchant ID = Store ID).