Currently, the Manual Exchange Rate feature is available to all.
However, ApprovalMax Administrators can restrict specific Requesters of Purchase Orders/Bills/Expenses to change the exchange rate manually during request creation.
This feature is available in beta, please contact support if you're interested in giving it a try.
This is how it works
Select your Organisation in the main menu and open Approval workflows under Workflows and settings:
Select the respective workflow:
In the workflow, open the Requester matrix:
Tick the checkbox for "Allow to use a manual exchange rate" next to the Requester(s).
When ready, click on DONE and update the approval workflow.