When changing the board and saving the theme is not applied and then the forum is displayed without any styling at all. 

 Broken-Theme.png You have insufficient rights to see the content.

From chrome console.  console.png You have insufficient rights to see the content.

Your old themes from pre 2.22 will not work!

P.S.: You can attach images by drag & drop them directly in the editor 😉 

I am trying to get back to the YAF theme, but it doesn't appear to set correctly. it looks like this issue happened when i selected an old theme *brainfart!

What themes are compatible with 2.3.1? are there any?anyway I can get back?? 

Thanks for poking me in the right direction! Also thanks for the image tip 🙂