When we create a Currency Type custom field, it only accepts two decimal places. If we source the Exchange Rate field to a Currency Type custom field, the rate will be rounded off automatically. There are instances that this affects the result when the custom field is used in a calculation.An alternative is to create a Decimal Type custom field then use a formula to convert the Exchange Rate value to a number. Below are the steps.
1. In the Custom Record page, click on New Field.
2. Provide a Name.
3. Set Type = Decimal Number.
4. Uncheck Store Value.
5. In the Validation & Defaulting tab, set Default Value =
6. Change the `transactionparentfield' to the custom field ID of the Parent Transaction.
7. Click Save