How to change product description to always display in English in pdf invoice

[Simon Lee]

Hi,

I have a website that have English and Chinese that can be displayed. However, the pdf invoice generated by PS in the BO (clicking the document icon in the BO in the order page on the PDF column of a "Payment accepted" row) displays the product description in Chinese and the Chinese character all appear as little squares as enclosed picture.

I would like to know how I can set the language of the generated pdf invoice to be always in English. Please advise. Many thanks!!!

Regards,
Simon Lee