How to fix VBA in Excel not support font (Lao)

Dear All in community

Now I try to use VBA in MS Excel to do some functions but I see some errors in my language it's show "???????" in string

please guide me on how to fix it.

my string is the Lao language 
My country is "LAOS"

My Keyboard use is "Lao"

I have attached the original file functions and capture screen when I typing