Hi there,
It's awesome to hear that you're taking advantage of the Multicurrency feature in QuickBooks Online. This feature allows you to conduct business with foreign funds, and keeps things simple in your books by doing the exchange rates and calculations for you. If you're trying to generate invoices in USD and accept Payments, you'll run into a road-block. I'll explain why.
At this time, QuickBooks Payments can only be used to process Canadian currency transactions. That's why the box at the top of the page for you to select Payments won't allow you to check it off.
I know how handy it would be to be able to accept payments in USD. I'd be happy to submit your feedback about this to the product engineering team. I'd recommend for you to submit feedback on your end as well, by clicking the Gear icon > Feedback. Your thoughts are valued, and we want to do everything we can to continually improve the product.
I hope this helps clear things up for you. If you have any other questions, please reach out to our tech support team.
Cheers.
