Each of your devices contains a complete copy of your data, at least the latest version of it. This allows writing offline. That data is synced when online and across your devices. It is possible that one device will not have the same content as another if one or both of them are offline. The way syncing works is each device sends and receives changes, not the whole project data. This both keeps the bandwidth requirements low (essential for mobile), and keeps changes from one device from overwriting those from another. They merge instead of overwriting each other. So your work is stored separately on each device. The entire change history of each project is not stored by default on each device, because generally it is not needed. We are looking at a feature called Versioning which will allow you to sync the entire change history to your device and view your project at any given time. This will take more bandwidth and storage, so we are looking at various ways to potentially optimize this.