I often use simple alt codes (e.g. µ, °, Ω, ±, in the sub 256 range) in Microsoft products like Word, Outlook etc., and usually they work fine. But occasionally the software insists to change the font, and the font appears random. For example, this morning in an Outlook email it changed to "Malgun Gothic".
I guess it has to do with the default font for the document or email, but so far I can't find "Malgun Gothic" anywhere in the styles for the email (HTML).
In any case, I don't understand why the font should change for simple alt codes as these are just more characters in the original 8 bit ASCII set, or why it does it randomly.
This effect has happened with several PCs and different versions of Windows.