Hi There,
You probably imported the demo that displays different content for desktop and mobile (multiple contents on the same page). You can verify that clicking the mobile icon beside the save button in the cornerstone. Then click the mobile icon to simulate the device.
When you inspect a section or some element, you’ll notice the HIDE BASED FROM DEVICE WIDTH option. And that’s where you can hide them to specific devices. And your sections uses this option to present different content for desktop and mobile.
Hope this helps.