Is it possible to get invoices in English and not a mix of english and Danish?

Hi there, userts.

Yes, you can. You can edit the invoice template and make sure the captions are all written in English. Here's how:

1. Go to the Gear icon and select Custom form styles.
2. Look for the existing template and click Edit. You can also click New style if you have not created any templates yet.
3. Proceed to the Content tab and click the invoice in the right-hand side.
4. Click Edit Labels and Widths and make sure everything is in English.
5. Click Done. 

Let me share this article about this feature for additional reference: Customise Invoices, Estimates, And Sales Receipts In QuickBooks Online.

As always, feel free to visit us again if you need anything else.