It should only affect the view of that document and should not affect your
normal.dot or other important settings unless something else is at work. For
example, if you have set defaults to automatically detect languages and one
of the users has used a different language and saved it to the document,
when it comes back, Word will detect that language and switch to it. Also,
Word documents tend to open in the view they were saved in - so that may
open differently than your default.

So check that your language settings are not set to Automatically Detect,
remove unwanted installed languages if possible and check that none of the
many other settings - particularly styles - are set to Automatically Update.

Terry