To access the Currency Exchange Rate page you must first go to the Currencies page, highlight the currency in question, and then drill down on the Exchange Rate. Alternatively from the Currencies page, you can highlight the currency and click Process → Exch. Rates as per below.

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Both would work exactly the same it's just a slightly different configuration.

Adding a Relational Currency Code

Currency Exchange Rates page has been changed for EUR to include USD as the Relational Currency Code as per below:

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