I'm trying to invoice in USD instead of EUR, but I can't change it?

You're unable to change the default currency set for your invoices in QuickBooks Online (QBO), @info1305. However, you can assign a foreign currency to your customer to record transactions the way they pay you with. Let me guide you how.

You can issue an invoice in a different currency in QBO when you turn on the multicurrency feature. (Please note that once you enable the said feature, you can no longer turn it off or change your home currency.). Then, you'll have to create a new customer profile and choose their currency from there. Here's how:

1. Go to the Sales menu
2. Select the Customer tab.
3. Click the New customer button.
4. In the Customer information window, fill out the needed information.
5. Go to the Payment and billing tab.
6. In the This customer pays me with field, select the customer's currency (USD). 
7. Select Save.

I've attached a screenshot below that shows the last four steps.

Once done, you can use the new customer profile in creating an invoice in USD.

In case you want to deposit a payment to a bank with a different currency, you'll have to use the transfer feature in QBO. To learn more about it, you can refer to this article: Multi-currency FAQ. It also includes answers to the most frequently asked questions about the said feature.

Please let me know if you have other concerns. I'm just around to help. Take care always.

@info1305 

You may have other options to invoice your international customers without enable the multi currency feature.

1. Utilize the payment service

https://veem.grsm.io/veems

2. Open a virtual multi currency bank account at TW and utilize the bank feeds

https://prf.hn/l/7gg1NWy