In this page of guidance it says:
You can also click on the banner icon on the left to make it the first scene loaded when you publish an app or when you export your project.
But those little banner icon seems to be disappearing in my editor.
Here is the screenshot:
It’s been moved to the publish step. That page needs updating 
Hmm, I don’t think that’s a clever move–it makes debugging specific scene harder.
Why do you think it makes it harder?
Because starting up from currently active scene is not always a suitable option.
(Visual Studio Code is smart, be like VSC)
BTW I found that occasionally my project would always startup from the firstly created scene when debugging. That’s kinda annoying.
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)
For context, what would you like to do? What feature would you like to have?
Thx this helps.
I would like to have a feature that allows me, say, to execute a spefic set of code before/while debugging (in contrast with published ver.) or startup on some other scene while in a scene.
Yeah, the ability to launch any scene or a specific scene from the launch button would be great.
While each scene’s launch tab URL is unique so you can always load the same scene via keeping the URL bookmarked, it doesn’t allow you to launch a startup scene and then the scene you are in.
You can write some custom code in your own startup scene to make this easier (eg a debug menu).
