Hi Kenneth -
Unfortunately, there's no way to change the default scene in the current version. I do have plans to enable some sort of rolling state-saving (/auto recovery, etc.), which would involve loading the last app configuration at startup, but I decided it wasn't worth holding up the release to implement this feature. At the moment, the app starts fresh with the default sounds if it is closed.
If you would like to get rid of your old samples, just delete the Borderlands playlist from your iPad. You can also enable "delete offscreen sounds" in the settings menu, which will allow you to quickly swipe the default sounds offscreen to delete them. That's probably the fastest way of clearing the screen on startup.
Hope this helps!
Very best,
Chris