Configuring your scenes
When you first open Atavism all of the scenes are defined already. If you open the original scenes and begin working on them, you will have your changes overwritten if you reimport or update Atavism. Unity uses a GUID system to identify files and store data in them. If the package you are importing has files with the same GUID as in your project, the files will get overwritten and any custom changes you make will be lost. Always create new items from the original. In the tutorial video above, you will see the items being created.