The content settings of the Instant Apps configuration window allow you to select or change the content to display in the app. Depending on the app, you can choose a map, scene, group of content, or add sections to display a variety of content (such as maps, scenes, apps, image and PDF files, and videos).
If you need to edit the map or scene used by your app, you can click the provided links in the respective settings to open Map Viewer or Scene Viewer. Some apps have a details panel that's populated by the description from your web map's item details. You can click View item details to open the item page and edit the description to fit the needs of your app.
Note:
If you want the details panel to include different content than the map's description, switch to full setup where you can provide a custom description in the About settings for some apps.