Whenever I was creating a new Word document I had also to change the Paper Size from “Letter”, that seems to be the default Word size, to A4, which is what I usually need.

If you face this problem yourself and you’d like to change the default paper size of MS Word, open your normal template (normal.dotm).

To find its location go to Options > Advanced: File Locations).

Change in the normal template the paper size to whatever you like, save, and enjoy!