Manually set the rate in Journal for Translation of Amount to Amount secondary currency

I am working on Microsoft Dynamics AX 4.0.

I have a company in the system for which the Amount columns in the accounts are in NOK and the Amount secondary currency is in USD.

When I record a new journal, I am able to set the exchange rate based on which the amount currency (Dr or Cr) is translated to the Amount. 

But I have no control on the amount rate at which the amount is translated at the Amount secondary currency.

I understand that the amount is translated to amount secondary currency through the rate at the corresponding date in the Exhange rates table.

So if I want to control the rate for the translation to this amount secondary currency I have to go and edit the exchange rate table.

Is there a way to avoid editing the exchange rate table and set a secondary rate for example while recording a journal in order to control the translation of the amount to the amount secondary currency?

I noticed that when recording a journal, in the General tab, under amount category, there is an option secondary exchange rate but this is 0 and is disabled.

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Thanks.