Word does not change to .pdf from .docx when exporting as PDF.

Every time I "Save As" and choose export to pdf while in Word, it seems to convert the document, but still saves it as a .docx file type so that when I try to open it, it says the file is corrupted until I manually change the file extension to .pdf. When I do that it opens right up as a PDF in Acrobat. On my PC, when I click "Save As" and choose .pdf as the file type, it actually saves a new copy with a .pdf file extension ands opens it up for me in my pdf viewer. I am fairly new to Macs (recent convert), but I do this a lot and need to know how I can fix this.