I cannot edit or move topics

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.