Takis:
First you need to store the scene (PhotoRendeing Settings > Scene > Store Scene As...), then you will be able to export the scene (PhotoRendeing Settings > Scene > Select and Manage Scenes...> Export), and use the same method to Import the Scene into another file.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David