Know where the money went

Track every account in its own currency, file spending under your own categories, and read it all back in one currency you choose.

Multiple currencies
Each account holds one currency. Every transaction is valued in your base currency when you record it, so reports never shift when rates move.
Transfers, not double counting
Moving money between your own accounts is a transfer, converted if needed and kept out of your income and spending figures.
Bring your history
Import a CSV and see exactly what it will create before anything is written.