the brush is not called scatter, but spread xD
fast tutorial on clouds like the ones in here:
same method here but with more blur:
similar process, but with the clouds on a separate layer instead of the same layer + using round and flat brushes:
;-; my first tutorial hope it's okay.
I personally don't like reading tutorials much, I can only follow through half of them most of the time, especially cloud ones. So I hope this can be easy to understand and follow ;u; and moreover easy to do!