@1vincent1 The base currency of the project is always the company currency and it cannot be changed. If you can explain your requirement, we can try finding a way. Let us know.

You probably do that in the project settings themselves, the base currency is probably the company base accounting currency, but in the project you can work with mulitple currencies.

What are you trying to achieve exactly ?

We just want to follow a project in a  foreign subsidiary with a different currency that the one define for this overseas company.

Have you looked into these settings ?

Or in Aurena/Cloud, in Project Setup Parameters: