Hi,
By default, when you drag a new chart from Tool pallete, it's in overlay mode. You can change it to stack mode by pressing right click on chart then go for stack plot option. When you change to stacked mode, again if you press right click, you will see overlay plot option to change it to overlay mode.
Hope this helps. Your feedbacks are welcome.
Wish you a happy new year!!!
Best Regards,
Nirmal Sharma
India