How do I change the default window size?
Open a program or an app. Change the default window size and resize it as per your preference. To lock the window size, right-click in the upper-left corner of the app or program window and select 'Size'. Place the window in the desired location.
How do I change the default window size in Chrome?
You have to right-click on the right of your tab and choose "size", then click on your window, and it should keep it as the default size. confirmed working windows 10 chrome 63!