What you can do is:

1: Make a new folder in the Bryce installation folder which should be C:/Program Files(86)/DAZ 3D/Bryce7. Name the folder to something like "My Default Scenes" or whatever you want.

2: Make a scene or several scenes the way you want them and save them to that folder. Save them with names that remind you what the scene looks like.

3: Open the new folder and RIGHT click on the scene icons one at a time and click "Send to" and then "Desktop (create shortcut)" Clicking on any of the desktop icons you created will open Bryce and load in that scene.

When you open a scene to work on, save it to where you normally save your work so you don't overwrite your default scenes.