My phone is missing the duel window switch. I took a picture of the screen but am unable to post it. Under smart settings it has two options Quick cover view and pen. No duel window
there is no switch in settings. you have to have android 7.0 or greater and you tap and hold on your square window key at the bottom (key on the right along with your back and home keys) for 2 sec to bring up your second window.