Not sure, but might it have anything to do with “smart quotes” that are in Microsoft Word? They’re the “curly” quote marks (and also apostrophes and single quote marks), rather than the “straight” quote marks. That might happen when any text with smart quotes is directly copied from another source, without first changing the text to “plain” text.
Below is an example of both types of apostrophes and quotation marks in a pre-post composition AND the result after posting, or previewing both:
