Currency rates are constantly changing, but we keep the currency rate fixed once the expense has been made. The only way to adjust the currency is if the expense is edited and a different currency is chosen.
When you request to be paid out, you will be paid in U.S. Dollars. You can always find the cost in USD under the converter in your expense:
The amount shown for each participant will be in the currency rate chosen, not in U.S. Dollars.
Once a participant is notified that they owe money, they will be shown the actual amount in USD to avoid confusion.