When I print or email invoices to customers, I end up with an extra line in the address with the capital letters 'LO'. Any ideas why?

Hello, @enquiries20.

We can perform a few steps on how to fix the extra line in the address. Let's check your Custom Form Styles and check the customise info. Here's how

1. Go to the Gear icon.
2. Under Your Company select Custom Form Styles.
3. Choose Invoice then click the Edit button.
4. Go to the Content tab to customise and edit the header, form, display of the invoice template.
5. Click Done.

To know more about the process, please click this article: Customise invoices, estimates, and sales receipts in QuickBooks Online.

I've included, this article on what to do once you've done creating invoice: How to email or print an invoice.

 Please let me know if there's anything I can help. Take good care.