I have word 2010 and also wanted to do that (coming from WP 5.1 for DOS). But I also could not get it to do that by default. So I made a macro that does it. This macro does many things, but one is to change the background color. Good luck. My only other suggestion is to change the Normal Template, but don't quote me on that because I am not sure how to do that or if it can be done. Do you send that work to an office, and if so, does it show that different color on their end?