Error - different currencies

What causes this issue?

You tried to create a (top) position in the capital investment program
&V1&/&V2&, and you tried to assign this position to controlling area
&V4&. This is only possible if the investment program and the
controlling area manage the same currency. However, the currency in
controlling area &V4& is different from the currency &V3& in the
capital investment program &V1& - &V2&.

System Response

The system rejects the controlling area.

How to fix this error?

Please create only (top) positions with a controlling area that
manages the currency &V3&.

Error message extract from SAP system. Copyright SAP SE.