From the Lines tab

If this feature is enabled, you can choose a recent work breakdown structure directly from the Lines form by following these steps.

  1. Open a document and if it is not already selected, click on the Lines tab.
  2. Select a line item by selecting its line check box.

    The fields below the line items list is populated with values from the selected line.

  3. Select a recently used work breakdown structure from the Work Breakdown Structure list.

    If the necessary work breakdown structure is not listed, click Choose WBS. The Work Breakdown Structure Code window is displayed where you can choose a work breakdown structure.