An existing Invoice/Quote Template can be changed at any time, and Invoices/Estimates that use that template will be automatically updated (Web-View only). However, we do not pass edits made to the Notes field to existing Invoices/ Estimates.
Invoice/Estimate templates can be edited by going to Settings > Invoice Settings > Invoice & Quote/Estimate Templates. You can quickly edit a template on an existing Invoice/Estimate by using the Edit option in the page header.
All new Invoices/Estimates will use the updated Invoice/Estimate template.