The cello staff from your older preferred file shares its MIDI channel with another later staff that uses a String Ensemble 1 instrument patch. If you want your new file's cello staff to sound like an ensemble, you can simply set it to also use that same patch:
!NoteWorthyComposerClip(2.751,Single)
|Instrument|Name:"String Ensemble 1"|Patch:48|Trans:0|DynVel:10,30,45,60,75,92,108,127|Pos:8|Wide:Y
|Note|Dur:Half,Slur|Pos:3
|Note|Dur:Half|Pos:5
|Bar
|Note|Dur:Half,Slur|Pos:4
|Note|Dur:Half|Pos:2
|Bar
!NoteWorthyComposerClip-End