Exchange rate differences automatically goes into the bank charges which is wrong

Version: SAP Business One 8.82 (8.82.073) PL: 10

Localization: Sweden

SBO user of Sweden is receiving from some customers payments in a different currency. Sometimes the payment is higher than the amount in SBO. Currently the SBO system will book the calculated differences automatically into the bank charges which is wrong. It should go to exchange rate gains and losses. Where should be wrong in SBO system? How to correct it?