Window size or camera resolution?

There is no description about Window size or camera resolution of Gdevelop. So guys please tell me Which one to use to change the resolution of the game? Can anyone please explain a bit about these" functions" (IDK how to say it). Please!

Right click the name of the game under scenes, and click edit property. You can change dimensions there, default should be 800x600.

Also, you can use these actions at scene start to toggle fullscreen :
change window size to ScreenWidth()xScreenheight()
change camera size (camera 0 and “” layer) to to ScreenWidth()*Screenheight()
fullscreen “on” keep proportion

I think I have to change both

You don’t need to change the window size as you already set it to fullscreen. However, you’ll have to change the size of the camera.