Skyboxes problem

I have recently discovered that Unity has got new Skyboxes. I used to use the typical skybox but when I replaced it by the new ones, something went wrong. I thought that it was a problem of the resolution but the images are high resolution.

Original skybox:

New skybox:

Has anyone know the solution?

change the quality?

How? I have changed everything and it isn’t enough. :frowning:

Anyone?