AI, which isn't guaranteed 100% accurate, offers this..
"Automatic Beaming: Users can automatically add or remove beams within one staff by toggling "Automatic Beams Mode" in the Notation toolbar, which does not produce cross-staff beams.
- No cross-staff tools: Reportedly, there are no available commands or shortcuts within Crescendo for cross-staff note assignment or beaming.
Alternative Approaches
Workaround: If cross-staff notation is essential, compose all relevant notes in a single staff and group them visually as needed, but true cross-staff beaming remains unavailable.
Export for advanced editing: Export the Crescendo file (e.g., as MusicXML) and open it in a program like Musescore, Finale, or Sibelius to perform cross-staff beaming.
Manual adjustment (inefficient): Some users might try to visually fake a cross-staff beam using text or graphic elements, but this process is cumbersome and not robust for most musical needs." Take a minute to file a suggestion.