You cannot change the bold phase dates in the Task Data view of the Gantt chart. They are a summary of the task dates for a particular phase and are view only. You can revise phase dates by changing task dates within the phase.

To change phase dates in Chart view:

• You cannot directly resize a summary bar. You can extend or move the blue task bars within a phase on the chart, and Project KickStart updates the summary bar.
• To reschedule a phase on the chart, drag the summary bar to a new date and all of its tasks (or a task and all of its subtasks) will move with it.