How to record exchange rate differences?

Good day! This year, I invoiced income in a foreign currency, because that’s what was agreed with the customer. My sales invoice therefore neatly states the amount in the foreign currency and in euros, according to the daily exchange rate on the invoice date. Unfortunately, the amount that ends up in my bank account a few weeks later is slightly different from what is stated on the invoice. I read on the internet that I should enter this as an “exchange rate difference”. Does anyone have any idea how to do this in Dexter?

(Since Dexxter is not updated to invoice in a foreign currency, I have loaded my sales invoice as a historical invoice and simply entered the income in euros.)

Thank you very much!