I’m still not quite sure what the context is so I’m going to cover all bases:
When launch the project with the editor from the dashboard, it will always ask you what scene to load.
When using the launch tab, it will start from the scene that the editor is in (the end of the URL for the launch tab is the scene id)
When publishing, you will always need to check what scene is ‘bookmarked’ to be the first scene that loads when users use the publish link. (Yes, it’s annoying that it doesn’t save your settings between sessions. There’s a feature request for this)