Typically you would start a new project for each scene then combine them in an external video editor.
Note that using a "Scene" (i.e. a pre-built scene with all the props already laid out) changes the scene for the whole project.
If you create your own setting, by placing individual props, you could possibly use other areas of the stage for a different scene/setting but is not really recommended.
See my CTA Tutorials on the YouTube channel CTAStepByStep
Check out EZColors for CTA. The easy way to change Render Styled (RS) colors.