How do I change the window size in Construct 3?

Hi, I would like to know where I can change the Window Size in Construct 3. It's now showing in the Project properties in Construct 3. THANKS!!

I meant "It's NOT showing..." Sorry!

It's called "Viewport size" in C3. It's a better name for the property, because that's what it really changes, it doesn't actually have much to do with the window.

Thanks, Ashley!🙏