You can use the Edit > Filter to horizontally select your notes for each (depending on how they were input either as separate voices or as a stacked (chord)).
If you were not consistent in how you input them (depending on different or same rhythms etc.) you might need to use both filters so you can cut/copy paste or [alt-M] as @MarcLarcher indicated.
Edit menu > Filter, Different rhythms, different voices
Same rhythm, stacked
