How do I customise my invoices?
Login and go to Settings > Appearance.
Scroll down to the section marked Template and you'll see an assortment of options, as well as the option to upload your own custom template. Custom templates are out of the scope of this article, but for more information you can go here.
Select the template of your choice (or the one you just uploaded). You can also change the dominant colour of your invoice, choosing from an assortment of predefined colours or picking your own custom colour.
Once done, click Update appearance at the bottom of the screen to make the changes stick.