Skybox Problem

Hello I’m new to the VRCHAT creating worlds using unity, it’s fun but had an issue that ruined every fun I had, I did a world with everything but I missed putting a skybox to make it look beautiful, I followed the simple steps of how to put a skybox I just took the material and drag it to the sky, I even did the rendering steps to drag the material and put it in the skybox material, It changed but when I test my world Nothing changed it’s the original skybox, not the one I tried. Actually not only me having this kind of issue me and my friend so.
please help us, thank you <3