All the templates used by the plugin are available in the templates path templates -> yith-pdf-invoice.
To overwrite each document template is essential to repeat the specific files in your theme “woocommerce” folder (in case it is not included, you must create it).
Copy and paste files in your theme “woocommerce” folder, by including them in the “yith-pdf-invoice” folder.
If you made changes and you need to check them, enable “Preview mode” option.
When option is active, you can generate your invoices and check the final result of your changes without any increase of invoice counter.
If provided, the automatic generation system of invoices will be disabled and any generated invoice will be hidden to user.