All the templates used by the plugin are available in the templates path templates > yith-pdf-invoice.
To overwrite each document template it 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.
Please note. Plugin updates will be ignored in your site for the files you have overwritten.
For the Black & White template or the Modern Stripes template, dedicated folders are added.