Hello tomtomx12,
Welcome to Community! I would be happy to share some information, so you're on the right track with your QuickBooks goals!
If you've turned on multicurrency, you can set a default currency to your customer profiles. This enables you to easily invoice them with the appropriate exchange rate. Please be advised that QuickBooks Online Payments, is only available for Canadian payment methods, so payment options will not populate on invoices for customers outside of Canada.
Should you require additional assistance, please don't hesitate to contact us outside of Community. It would be our pleasure to work with you in real time, and ensure you're able to accomplish your QuickBooks goals without delay!
Feel free to reach out again, if you have any other questions. We would be glad to assist!