Changing the Key for Transposing Instruments

Howdy. I finally found a way to fix the problem I was having, and I wanted to share it with y'all! https://youtu.be/mFBSSAQYVew

I'm making a warm up book for band where every key is involved. Some of the key signatures involved transposing instruments to read in keys with seven sharps/flats, which I did not want, but when I tried to drag a new key over to change, it would change it for all instruments. But now it's fixed.