I'm using Word 2016 on windows 10. On my computer, I have 2 keyboard layouts installed: English (US) and Vietnamese. Since a lot of windows shortcuts I use require me to keep the English keyboard layout, I turned off the "Automatically switch keyboard to match language of the surrounding text" in word.

But now there's a problem: every time I type anything, word automatically switches the proofing language to English.

I've tried the following:

1) Setting Vietnamese as the default proofing language for normal template
2) Setting display language and help language as Vietnamese
3) Unchecking the "Detect language automatically" option.
4) Selecting all text in the document and manually turn proofing language into Vietnamese

But none of that work! The moment I type a single character, even if it's just a space, the proofing language immediately switches back into English to match my keyboard layout.

Is there any way to fix this (without having to change the keyboard layout itself)? In other words: how can I make the keyboard layout independent from the input language in Office 2016?