Help with segment editor sphere brush

Hi There,

I am trying to use the spere brush option for thresholded segmentation in “segment editor” module.

Slicer version: 4.10.2
OS: windows
Data : 3D (dicom2nii converted)
Expected behaviour: using one step of paint along with sphere brush, to segment a structure from all slices.(Expect volume filled with label number in Y and G view panel)
Actual behaviour: sphere brush functanality does not work for entire volume. Paint is only applied on single slice.(check Y and G view panel)

Any guidance or help is really helpful. I have tried to follow the youtube tutorial
segment editor Tutorial

Looks like the brush radius is smaller than the slice spacing. What happens if you use a bigger radius?