How do I using using windows media 10 burn music to a CD in mp3 and use mp3 as the default burn?

Answer 1

go to tools then options - all the configuration is there

Answer 2

On ver 10, they hide the options. Just right mouse click anywhere above the words Library / Rip / Burn.
As someone else pointed out goto Tools / options / Rip Music.
Where it says format, pull down and chose MP3.
At that point push or pull the sliders left and right to chose the quality. To the right is better sounding (uses more HD space, to the left is worse sounding (uses less HD space).