Change what appears on an invoice

Open the invoice for editing and use the settings button in its toolbar — the gear on the dashboard, the Settings row in the mobile app. Notes and terms, the footer note, the signature block, the line-item wording and which custom fields the customer sees are all controlled there. Defaults come from your organization settings and are copied onto each document as it is created, so changing a setting there affects new documents rather than existing ones; any single document can then be changed on its own. There is no gear on the invoice detail view — you have to be editing it.