Moved the game to a different computer and ended up with the small play window problem.
Fixed it with: changed the size of the screen (slightly larger than original) and clicked maintain ratio
Then on the game icon I right clicked and it has an option troubleshooting--- compatibility question. Clicked display problem, and a box came up that had several options. One of which is about not showing correctly due to the original size of the screen. Clicked that box and then test.
Imp came up full size on the size I choose to play the game. Hit the option that it worked and now I hit the launch button it goes to new full display.
Do not know if this is well known. But worked for me so I thought I would put it up.