In your admin section, you will have the option of turning on or off the Hide Closed Jobs feature. What this will do when enabled is ensure that when you are job costing expenses, any job that is already closed will not show up when searching through your list of jobs/phases. You can turn this feature off at any time if you prefer to view closed jobs when job costing.
This feature can be found in the admin section, under the customize tab, as shown here:
Located just below is a separate option to hide bidding jobs, if you'd prefer that jobs currently in the bidding/out for signature status do not show up in searches when job costing.