[Resolvido] How do I reset/switch the currency to the default currency at checkout?

Background of the issue:
I have multiple currencies setup in Multi currency WPML. But the payment gateway company I'm using (Xendit) only supports IDR, PHP and US dollars. If a user sets their currency on display pages e.g GBP, AUD, I need the currency to switch back to the default currency (Indonesian Rupiah (Rp)) on the checkout page for the payment gateway to work.

Symptoms:
I could not find any documentation on doing this.

Questions:
How do I reset/switch the currency to the default currency at checkout?