how to change layout when the option isnt there?

im trying to change my layout and i did all the steps correctly, i found the layout i wanted and copied the code and when i went to my about me section to paste it in the html/css code the box wasnt there. i refreshed, tried a different browser, even gave a friend of mine my account so they could try it themself but nothing worked. i verified my email, so its not an issue of that. what do i do :((