There are a variety of ways in which you can change the start and end dates of a project task.
Editing Tasks in the Tasks Pane
To edit the Start or End date of a task in the Tasks pane, do one of the following:
Click the Start or End date and enter the date you want or click the calendar icon and select the day you want. If this changes the length of the task, the Duration field is updated. If the task is a child task, the Start, Finish and Duration fields of the parent task is updated if the change affects the overall the length of the parent task.
Increase or decrease the number of days in the Duration field. The End date of the task is updated. The End date of parent tasks is updated depending on the End date of other tasks within the hierarchy.
Editing Tasks in the Schedule Pane
To edit the Start or End date of a task in the Schedule pane, do one of the following:
Hover over the task that you want to move. When the cursor icon changes to a cross, drag the task to the position on the timeline that you want. The new Start and End dates are shown as you drag the task.
Depending on whether you want to change the Start or End date, hover over the start or end of a task in the Schedule pane. When the cursor changes to horizontal arrows, drag the start or end date to the position on the timeline that you want.
Double-click the task and edit the task in the Task Editor popup.