The best way to update the Order/Supply/Back order Columns of a job (rather than using the right click Stock Availability option from within the stock grid) is to edit the job list and tick Auto Pick stock at the bottom of the screen.
When you set a list to Auto Pick and the list is run it will tell you what is available.
If you double click on one of the jobs in the list, its availability is highlighted green, however Jim2 has not yet made the supply or back order adjustment for you within the job.
Be sure you are using Edit at the bottom of the list if you want Jim2 to update the availability within the job itself.
Now you will be displayed the job in Edit mode and the Supply or Back order number has been adjusted for you.
Further information: