Here some description of my problem.
1. I used Upfront Builder and edited the home layout.
2. Accidentally I entered the Upfront post/page editor and modified "this home post".
3. Then evergthing I changed in the home layout won't take effect because I think it's overwritten by the post content.
4. I can't find a way to undo what I have done in the post/page editor or delete the home post content.
5. I can still use the Upfront post/page editor but that's not what I want now, not layout builder.