How do I change my viewport and all layouts afterwards?

I want to set my Project to 3840x2160 Viewport Size and 16:Ratio, because actually I have something like 43:18 with black bars at all around.

If I do that and change a layout to a 16:9 like 1920x1080, some sprite are outside the window. How can I change that without setting all sprites in every single layout again? Is there a way to scale it?

No one?

construct.net/en/tutorials/supporting-multiple-screen-sizes-77 has everything you need to know, although it might take a little effort to apply.

You shouldn't have to worry about sprite sizes if you're using full screen scaling, as that is automatically taken care of.

You can get the window size via system expressions if you want fine control over high or low resolution assets, but that is usually unnecessary.

The thing you will need to adjust would be the position of the sprites depending on the position of the screen edges. The second page in that tutorial gives more information about that.