I prefer Nashville numbers for most songs, but for a few song my brain is too slow and needs the letters spelled out. Though I can change the global ‘Show chords as…’ setting when going to/from such a song, it would be more convenient (faster in a jam) if I could just override the display for specific songs so they locally latch to whatever type of display I always want for that song.
Or if I can download a faster brain, that’s a fine option too. 