Dears,
I am writing some kind of essay in Indonesian in Microsoft Word. Many of the words and clauses are in English. So I use multiple language proofing and enable "detect language automatically". But so far I wasn't able to observe the feature working. When I
type a new English word, Word doesn't detect it. Instead, it just marks with a red underline. To check if it's just a quirk in a particular document, I made a new document and paste some Indonesian sentences while using US keyboard languange setting and vice
versa. I waited a while but the proofing language doesn't automatically detect it.

How to resolve this, so that it will detect different languages automatically? Am I missing something here, or that's not how "detect language automatically" works?