Hi Jitendra,
If you have access to the Dev system,then goto VA02 and change the data or Quanitty ,save the data.
This should reflect in LBWQ,also in the change log of the Sale Order,Which is there in the TABs.You should able to change log as well with details as who changed ,what got changed and at what time.
The Other way may be to refer with SD consultant and incase there is any customozation in the Process then check with the ABAP Team on this particular Process.
Hope this gives an idea
rgds
SVU123