An oddball query. I've successfully created loads of practice songs in different keys.

Lately, I've noticed a kind of default error where the key in both some new and existing songs changes without my resetting it? It's almost like my default isn't Concert C and BIAB think it's a horn so maybe home key is Eb or Bb? If I try to change the top bar all the chords naturally change again.

I'm trying to fathom how this occurred, whether I changed anything but this is a minefield, so your advice & suggestions are most welcome.

Using Band-in-a-Box Pro 2023 for Windows (BBP-I)