You can create and save multiple headers and footers to re-use on invoices and proposals. Create these by going to Settings > Headers & Footers. To use these on invoices and proposals, just select them from the template drop-down menu at the top of the screen when creating or editing an invoice or proposal.
Header vs Footer
The header is placed at the very top of your invoice, above your logo and business address. This is a great place for you to write a note that you want your client to see immediately.
The footer is placed at the very bottom of your invoice, below your line items and next to your invoice totals. This is a great place for you to write a quick note reminding your client of something.
Examples of headers
"Here is your revised invoice. Let me know if the changes are okay."
"Just a reminder that our business address has changed. Please send all payments to our new address below."
"I hope you are having a super-sparkly day. I appreciate your business."
Examples of footers
"Just a reminder that your payment is expected within 30 days. Call me if you have questions."
"A discount has been applied to your total. Please review the line items above for details."
"Fun fact: This invoice was made with love while I was wearing my favorite t-shirt."