Chord symbols are essentially a system-attached item, meaning you only need to input them once but they can appear above multiple staves and in whichever layouts you like.
- To change which staves chord symbols appear above, see here.
- To change which layouts chord symbols appear in, see here.
I seem to recall there being an issue with how chord symbols appear in transposing layouts in the iPad version, which is probably the cause of your NC symbols.