If you click "Settings" at the top of your page and then select "Invoice and payment settings" on the left you will be able to see page below. Kindly scroll down to Payment Settings where you will be able to add any content you may want to appear in your invoice in the "Payment terms and bank details":
This will appear as below:
You can also add a letterhead to your invoices. This content can change per location. To do this click "Settings" then "Locations", then select the location for which you would like to add a "Letterhead":
This text will appear as below:
You can also set your invoices to show the patient DOB, name and insurance details in Invoice settings by ticking the boxes in the 'Invoice details' section:
These will appear on the invoice like below:
Please note that you can not change invoice numbers.