First, on the main page, click the "Cameras" button on the Main Page in the far left menu (Note: The Main Page is the Family Accounts page and is usually the one landed upon after logging in):

Then click the "Edit" button for the camera on which you wish to change the viewing hours, located to the far right:

Next, click the "Add Viewing Window", which will allow you to fill in Start and End times:

If you would like to have the camera broadcasting 24/7, remove all viewing times by clicking the "Remove Viewing Window" button. You will return to the "Hours of Operations" section of the Edit Cameras page and see the statement, "This camera Broadcasts 24/7."