Can't manually modify the currency Exchange Rate within Sales Order and Quotes

Can't manually modify the currency Exchange Rate within Sales Order and Quotes

Hi
 
We had been working with custom fields and templates in order to use different currencies ... and yesterday we decided to turn on the multi currency feature in zoho but after one day it seems very disappointing.

Besides your weird currency formatting (another post) we were required to input a FIXED exchange rate for USD and EURO, our local currency is Mexican Peso. And now when creating/editing Quotes and Sale Orders the exchange rate is LOCKED on that number, but that does not work for us, we need to be able to edit it manually case-by-case, the exchange rate changes daily, and for some scenarios it depends on the type of payment the customer will make, sometimes we have a weekly-monthly Exchange Rate for certain product sets.

There should be an option to both "select the exchange rate by day and have it automatically filled" but also to "input manually" if needed.

So to make it short, Zoho, can I manually change the Exchange Rate within Quotes and Sale Orders ?
If not, your Multi currency feature is useless to us.

Please help.