In this audio recorded in Portuguese language, I am going to walk you through some common mistakes that Brazilian English speakers are prone to.

Source language (Portuguese) => seu / sua 

Target language (English) => your / his / her

I would say that you must stick to these 2 fundamental rules.  

Question #1:  To whom are you referring to?

Answer:  someone in a 2-way conversation.

Question #2:  To whom are you referring to?

Answer:  someone in a 3-way conversation - referring to the 3rd person in the conversation.