As currency and exchange rate information is added, updated and deleted, the system retains the details of the changes. This allows you to track changes to the exchange rate value, identify who made the change and the date it was amended.
Open: Accounting System Manager > Settings > Currencies and Exchange Rates | View Currency History.
From the Name drop-down list, select the currency you want to investigate.
The changes made to that currency appear in the History pane.