Microsoft Word for mac.........change fonts????

Hi. got this Microsoft Office for Mac thing. Trouble getting it to do what I want.

Biggest problem right now is :

"How do you change fonts?'
I know....you go to the thing that says fonts and select one you like and pick its size and the computer says ok.

But then when you start writing, you're back to the same old font you tried to get rid of........
Spotlight is no help.........

Maybe YOU can help. I'm stuck.

Thanks Fred Bear