Exhange Rate not working in sales order

Dear all,

I am facing a problem with exchange rate, I have maintain exchange rate procedure in customer master with exchange rate INR 70 = 1 EUR, Now I am creating Sales order where as i m changing Exchange rate INR 65 = 1 EUR, in sales document header as well line item, but surprisingly system is not considering 65, it is only considering 70, But i want system must consider 65 which i m manually changing in sales order.

Please suggest me to solve the problem

Regards

Shambhu