It's good to see you here in the Community, winnie-lim. Knowing how multicurrency works in the system is essential to properly record your transactions. I'll be happy to share more on this.
In QuickBooks Online, posting your b/f inventory in a foreign currency is currently unavailable. It'll be based on your home currency setup.
As a way around, you can set up suppliers and customers in a foreign currency of your choice. This way, if you create a bill/invoice towards a USD supplier for example with your home currency being CAD, QuickBooks Online will display the total cost of the bill in both USD and CAD.
You can refer to the following resources below on how to add foreign customers and suppliers in QuickBooks. On the same link, you'll find steps on how to change the currency for existing clients:
Assign a foreign currency to a customer in QuickBooks Online.
Add a supplier with a foreign currency in QuickBooks Online.
I'm only a post away if I can be of additional assistance while working in QuickBooks. I'll be around to keep helping. Wishing you a wonderful rest of the week.
