My apologies, but I can not tell from your question which X,Y,Z numbers you are referring to.
The top panel of the WC Offset pages displays the current Work Coordinate position. The panel also displays (in columns) the Machine coordinates, WC Offsets and G92 offsets which mach uses to calculate the current WC position from the machine coordinate position.
Within this panel only the values in the WC offset and G92 columns can be changed by the user (See section 2.1.3.3 of the manual)
The values of the WC offsets show are the offsets for the currently active work coordinate system. Mach defaults to using G54. The currently active WC system is shown within, and can be changed from, the Work Coordinate offset panel.
If you are looking for more information about the controls on the WC Offset page, please see section 4 of the user manual.
If you are looking to learn about work coordinate systems and what they are, I suggest a good book about GCode. One example is “CNC Programming Handbook” by Peter Smid.
Dave