How to Edit PDFs such as Sales Orders, Sales Invoice, Purchase Order, and Packing List documents?

The Sales Order/Sales Invoice PDFs are in the GFERP managed package and cannot be edited directly.

You can clone them and then edit.

This applies to all PDFs created in the managed package.

For example, to modify the Sales Invoice PDF, navigate to Setup\Object Manager\Sales Invoice.

Then look for the Print Invoice button.

Click it to access the Visualforce page.

Then click Clone to create a new Visualforce page.

Modify the newly created Visualforce page for meet your requirements.

After you finish, you can modify the Print Invoice button to point to the new Visualforce page.