Paint Brush changing

[Sophie28788041wqbw]

Hi,

im semi new to illustrator and when I use my paintbrush it draws as a black line and THEN converts I whatever brush I have selected (like watercolour) I hate this as I always need to go back because it doesn't run out how I wanted. How can I change this? Thanks 

[Monika Gause]

You want a realtime preview of the brush? THis is only possible with calligraphy brushes.