Exchange gain or loss going to Unapplied Cash account after clearing

Receipt Creation @ USD (1 USD = 3.675 AED)

Confirmed Receipt   1000

      To Unapplied Cash  1000

Remitted the Receipt @ USD (1 USD = 3.675 AED)

Remitted Receipt  1000

     To Confirmed Receipt   1000

Clear the receipt @ AED (1 USD = 3.7 AED) & Bank Charges AED 50

Bank Account      3650

Bank Charges         50

        To Remitted Cash   3675

        To Unapplied Cash     25

In the above scenario why the exchange rate difference gone to 'Unapplied Cash' instead of Exchange Gain or Loss Account?

Regards

Uday