The details of currency handling (for invoices) are controlled by settings in the
You can adjust:
Which currencies the system is able to look for on invoices.
The currency notations that the system looks for by default, both when looking for the Currency field and when you specify currency notation for amount fields.
The three-letter abbreviation that the system (1) assigns to the Currency field when a corresponding currency notation is found, (2) uses in several dialogs, and (3) includes in the output.