CPlane moving

I have a problem with Set CPlane
I can set it to an orientation I want and save it under Named CPlanes.
Only trouble is when using it often jumps back to another coordinate system probably wcs.
Is this because I moved an object or block created with different cplane.
Why does this happen and is there a way round it?

Hello -

I need to know exactly what this means - what action causes the change in the CPlane? note by default CPlanes are set in one viewport only.