I don't find this a very good way of saving your information on to invoice.
1) For multi page invoices, using the footer, the payment information is printed on every page.
2) On estimates using the footer, payment information is still displayed even though it's not needed.
3) Using message to customer, the information is not saved in you have to write it every time.
I find it very counterproductive trying to put payment information on my invoices. It should be very simple and convenient but it obviously hasn't been thought about very well.