How to charge customers using Euros rather than Sterling

Hello there, Alan. You can send a bill using euros instead of sterling currency by turning on Multicurrency in your Account and settings. Make the customer inactive, then add them back through the New customer tab. Your past transactions will still be in QuickBooks.

To enable Multicurrency, go to the Gear icon> Account and settings> Advanced tab. After that, scroll down until you find the Currency section. Then select Edit, toggle the Multicurrency switch on, and tick the box next to I understand I can't undo Multicurrency. Choose Save, then Done. 

Please visit this article for further information on how to make customers inactive, then re-add them, and choose the correct currency: Set up and use Multicurrency in QuickBooks Online.

Feel free to comment below if you have more questions about QuickBooks.

I assume you mean you want to invoice a customer in EUR not change your entire system (i.e. home currency) to EUR.  For that you'll need multicurrency and you'll need to enable it and add the EUR currency (in settings). 

You'll also need to create a new customer, set up in Euros. 

Multicurrency is only available in Essentials or above.