In May 2018 the default site 'skin' for this site has been Wikia's Oasis default. You now cannot change this in the 'My Preferences' option.
This page will provide the links for users who want to switch from the Oasis skin to (2) PseudoMonoBook and (3) PseudoVector. You will first have to create a 'css' file. You do this here:
https://uncyclopedia.wikia.com/wiki/User:Username/common.css ('username' will be the name you have chosen as an account name here).