Some regions of loaded CT data are not showing in 3d slicer

When I am loading the data into 3d slicer some of its regions are not showing , but somehow when I am changing the master volume that regions are showing but I am not able to paint(Or edit them ) . Please help me in this

Extent of the segmentation is specified by the master volume that you selected first. See instructions for changing it here.

To show a volume in a slice view in full, you can click the reset field of view button. If you switch to a recent Slicer Preview Release then clicking the eye icon in Data module will show the entire volume by default (no need to click the reset field of view button).