I realise NWC don't apply correctly accidental:
An accidental applies to a single octave only.
In this example ↓ NWC play: F# F# F# | F F# F#
Agreed. However, for clarity, performers generally prefer to have a natural on the octave note if the accidental isn't meant to apply to it. Less chance of error that way.
You have discovered a longstanding bug in NoteWorthy. I won't bore and confuse you with all the links to the discussion. The bottom line is that there are no plans to fix it. :(
This is an architectural quirk of NWC. Note accidentals apply in all octaves within the bar. The way to avoid the problem at present is to always use the correct accidental in all other octaves of that same named note after you use an accidental in one octave of the named note.
The Warn column in Tools, Score Review (https://noteworthycomposer.com/nwc2/help/MNU_SCOREREVIEW.htm) will indicate the presence of any unassigned octave accodentals.
You can use Edit, Find (https://noteworthycomposer.com/nwc2/help/MNU_FIND.htm) to identify and correct any unassigned octave accidentals.