I can't change the appearance of my sims in CAS

If you haven't tried this before, you might reset your user folder.

As always make a backup of your game data before you start tweaking your game to have a fallback option if you don't like the result.

1. Go to your user folder, you usually find it in \Documents\Electronic Arts. It's the folder called "The Sims 4".
2. Move this folder to your desktop or another location of your choice. Just be sure to move it to a place you can easily remember. Do not copy or delete anything.
3. Launch your game. The game creates a new "The Sims 4" folder with default files and folder structure during startup. Your game will now probably work flawless. Create a household and test whether everything works.
4. Shutdown your game and copy your saves folder from the moved "The Sims 4" folder to the newly created one and check whether your saves also work.
5. If everything is fine, you can also copy back your other user data (like Tray, Screenshots etc.). Please do not simply overwrite the newly created "The Sims 4" folder with your old one. It's the trick to have those new files and folders in there, while your old ones are probably somehow damaged.

I hope that this procedure can help you.

If you have any further questions, please ask.