At the bottom of your posting window, next to Post Options, there is a little box labeled "Labels For This Post". Click on that box, and type in whatever you want.
Although I less than three the Calibri font, I will tell you how to change it because I am a good person. Under the "Home" Tab, there are multiple selections you can use as your default. Just go to the Blue and Purple overlapping "A's" and click. That 's labeled "Change Styles". Go to fonts, and I think what you're looking for is "Office Classic"