I know that Yahoo does not really provide good adjusted data of less important non US ETFs. We are at the moment testing if we could use free Quandl data instead, but this will take a moment to finish.
You can open the ETF csv files in Excel and edit your data this way, but from this moment you need to make sure that you never choose to download new data,because then your edited data would be overwritten.
You can load currencies using the Yahoo symbols (AUD=X for Australian dollar).
