Set a blank date for the exchange rate entry.

1.In Setup, click  Currency exchange rates.
2.Click the Exchange rate type drop-down arrow.
3.Select Default.
4.Click New.
5.Click the From currency drop-down arrow.
6.Select USD.
7.Click the To currency drop-down arrow.
8.Select AM.
9.Click Add.
10.In the Start Date field, click the calendar icon.
11.Click Today.
12.Click the Exchange rate field.
13.Type "5.00".