Accounts in other currencies and year-end revaluation
Bank accounts in dollars or other currencies, the exchange rates NaPa uses, exchange differences and the revaluation at the fiscal year's end.
When you add a bank account you can choose another currency. Its statements and movements are in that currency, and its sub-account sits under 573.
The exchange rate
When reconciling a movement in another currency, NaPa uses the rate the bank applied if the statement brings it. Otherwise, the one you choose in Exchange rates, in Banks: the ECB reference rates of the movement's day, or typing it yourself when reconciling. You can always change it on the movement.
If you collect an invoice in euros from dollars, the difference goes to exchange differences (668 or 768). A transfer between your accounts is reconciled on both with a single entry, at the rate the bank applied.
Year-end revaluation
At the fiscal year's end, balances in other currencies are valued at that day's rate, and the difference goes to profit and loss (668/768). In Banks › Year-end revaluation you see each account with its balance, its book value and its value at the closing rate; when you confirm it, NaPa posts one entry.
It's needed to close the year's last period. While that period is still open you can undo the revaluation and repeat it if the books change.
Updated