Thank you for reaching out to us, @firstname.lastname@example.org.
I'll be glad to help you with your default rate.
Yes, you can definitely change the default tax rate selection in QuickBooks Online.
You can also check on this article: The Value-Added Tax (VAT) registered for more information about adding VAT rates in the system.
We're always here in the Community to help if you have other questions related to QuickBooks. Stay safe!