Hello there. I'd be glad to help you upgrade your QuickBooks Online (QBO) version so you'll able to raise invoices in different currencies.
In QBO, you have to turn on the Multicurrency feature so you can use different currencies for invoices. However, this option is only available in Essentials, Plus, and Advanced versions.
To upgrade your subscription so you can use this feature, go to the Billing & Subscription page. Here's how: