After updating, click 'Example Page' on the page to get 404. It's a brief description of the concept of the page, so it's okay to just show the lecture screen. If you are uncomfortable with WordPress's default editor (block editor) when editing your text, you can install a classic editor. https://tiprelay.com/%EC%9B%8C%EB%93%9C%ED%94%84%EB%A0%88%EC%8A%A4-%EC%97%90%EB%94%94%ED%84%B0%EB%A5%BC-%EA%B3%A0%EC%A0%84-%ED%8E%B8%EC%A7%91%EA%B8%B0classic-editor%EB%A1%9C-%EB%B3%80%EA%B2%BD%ED%95%98%EA%B8%B0/