How can I customize the payment block in the Magento PDF invoice?
So if we want to customize e.g. the text/formatting that is printed on the invoice in case of "Purchase Order" payments we have to do the following steps:
- copy file app/design/frontend/base/default/template/payment/info/purchaseorder.phtml to your theme folder i.e. app/design/frontend/
- customize the file to your needs
Basically it is always recommended to activate the Debug Mode of the AdvancedInvoiceLayout extension for testing different layouts under System > Configuration > AdvancedInvoiceLayout. With activated Debug Mode the intermediate HTML file will be saved with each print of the PDF invoice, shipment or creditmemo into the directory var/tmp/invoice_debug.html. Therewith you can analyze and customize the HTML structure and CSS style sheets more easily.
However you are advised to disable this setting in production environments for performance reasons.
This process can be done analoguous for other payment methods as well.
Please see also how to customize the Magento PDF layout in general.