Log in to the HTML5 client.
Select the Work workspace, Gantt tab.
Select a project in the Project Data Selector.
Place the mouse pointer on the right-hand side of the task’s Start Date or on the right-hand side of the date on which its progress was entered and hold down the Shift key to visualize the Split () icon.
Hold down the left mouse button and extend the completed portion of the task to the desired date.