I want to create a brush of circles. Circles of line and not fill.
So, what I'm doing is listed below:

Draw a circle
Set fill to none and line to 2px
Select ‘Freehand and Brush Tool’
Select ‘Create Brush’
Enter your brush name
Set 'Type of brush:' to 'Scatter brush'
Select 'Create'

Now use the brush

Select the newly drawn brush with the ‘Freehand and Brush Tool’
Select 'Edit Brush'
Select the 'Fill Properties' tab
Select 'All brush colours' under 'Local colours replace:'
Select 'Save'.

Having done all that, why can't I now change the colours of the circle line to what I want?

I'm sure I've done this before or am I just dreaming?