When topics jump back after you moved them, you’re using an auto layout. Click here to learn more about this and how to change this to a free form layout.

iPad&iPhone and Android

If editing is not possible, for example moving a topic, most likely you’ve zoomed out too much. Zooming out beyond a certain level will switch the mind map to read-only, this prevents unwanted changes.
Zoom in to bring back the normal functionality.

If you prefer to work zoomed out, you can adjust the editor scale in Preferences.