A family of Microsoft word processing software products for creating web, email, and print documents.
The converter in Word is not capable of creating high quality PDF images. You have to use a different program to convert your Word documents to PDF. You can try using Adobe's on line Word to PDF converter,
See https://www.adobe.com/acrobat/online/word-to-pdf.html
But if that doesn't give you the results you're looking for, then you will need to use Adobe Pro or another program. Some are free.