I'll share some inputs about how home currency works when multi-currency is turned on, su-tan.

Once the Multi-currency feature is enabled, you'll no longer deactivate or change its home currency.

You can check these resources to learn more about how QuickBooks Online handles multi-currency:

• Set up and use multicurrency in QuickBooks.
• Turn on and use multicurrency.
• Multi-currency FAQ.

In addition, you can designate a foreign currency to a customer in QBO to enable the recording of transactions in which the customer pays you.

Here's how:

1. Navigate the Customers & leads tab, and select Customers.
2. Click New customer.
3. In the Customer information window, fill out the required information.
4. Select Payment and billing.
5. In This customer pays me with field, pick the customer's currency. This is the currency that the customer uses to pay you for products or services.
6. Tap Save.

Keep me updated if you have other questions while performing tasks on your account. The Community is always ready to help you out.