I had a
heck of a time figuring out how to ensure Outlook always started with a format
I liked. It turns out this is more complicated than anyone would imagine. But
once I explain it, you should be able to make your changes in about ten
minutes. You'll be able to click new message and just start typing without
making any formatting adjustments. (Sorry this is so long and has no pictures. If I didn't have a day job, I would add screenshots.)