I just started using Builder. I know I can change the dimensions of the volume before creating it, but how can I change the size on the view window so that is more manageable for adding other volumes and designing?
Direct geometry editing in the View Window is not available. Though, you can use the Transforms->Scale to change geometry size.
If you are referring to the view controls, then you can zoom the camera in an out using a mouse wheel, or set the left mouse button as the zoom control according to "Camera View Control and Entity Selection". Note the Fit All button will also fit the view window to the extent of the geometry in the view.