Key Signature Change

In the current version - 1.3 - key changes are per staff. In the nightly builds for 2.0, it defaults to changing all staves at pnce, because that's definitely the way the vast majority of music works. But if you are deliberately writing polytonal music, you can get that effect - i think by holding ctrl while adding the key signature. But be sure this is what you want. It's incredibly unusual. Perhaps you are thinking of music for transposing onstru,e s, whee instruments appear to have different key signatures because they transpose differently? You still create these by adding the same key signature to all instru,e s at once. They will automatically show as the same while in Concert Pitch mode, and automatically sow transposed when you turn Concert Pitch off.