There are two ways to customise your Invoice PDFs: the PDFs settings panel for the common details, and HTML Templates if you want full control over the layout.
Editing the standard PDF details
For most changes you won't need any HTML. Navigate to System > Settings > System Customization > PDFs, where you can set:
Your PDF logo.
An Invoice statement prefix.
Your Invoice payment details, such as bank details for Clients paying by transfer.
Page suffixes for Invoices, Credit Requests and Payment Orders.
Full customisation with HTML Templates
If you want to control exactly what appears on your Invoices – including styling, branding, and what details to show – you can use HTML Templates.
Navigate to System > Settings > System Customization > HTML Templates. From there you can create or edit an Invoice template using HTML.
The HTML Templates page, under System > Settings > System Customization > HTML Templates.
Note: You can only have one template of each type, apart from email templates. To change a template's type, you'll need to delete it and create a new one.
Note: Editing HTML Templates and PDF settings requires permission to edit Company settings, so these options will be greyed out for Administrators without it.
You can find out more about HTML Templates here.