How to get the 2nd window in Multi-window to go back to side by side?

[Andy847]

Hi, I remember playing with the Note 4 in the store for the feature to open up the 2nd window in multi window and being able to move around and resize it. It took a best buy sales rep to show me how to do it. I still don't know how to get it back to side by side after it opens the window in proportions of the screen. I know to just tap the top circle and the options to full screen and minimize the window do, but when I tap the 1st one which shows the finger tapping the front window of two, it just minimizes into a small Icon that you can move around. How do I get it back to side by side view?

If I try to resize the window by the outline of it, I can only move the corners and stays the same proportion of the screen.