First time post

Hi everyone, I've been watching this community for awhile, and just joined. So with out further to do...

Alright, I've been trying to color an icon with the paint brush, and every time I find the color I want- it won't let me change from purple.

So I basically have no clue whats going on O_o, and sense you all are like the geniuses of icons- I figured you could help.

Heres 2 screen shots:     &  

I really do hope you see what my problem is- and can help me