Trouble with theme changes? This tip may come in handy:

In reply to a query: I'm trying to switch to the Cypress theme … It doesn't look like the theme when I switch.

… Do you have another custom theme installed that might be interfering? There’s probably an error on the Design page if it didn’t work… Try making sure there’s no custom theme, and then go into Account → Show logs → Rebuild to make it do a full rebuild. (Not usually necessary.)