[LD Jackson]

When you click the [#] button in this situation, the key changes to C# and all flat chords in the song become sharp. That's the nature of the key.
However, when the key is C, F, ..., the chords are always displayed according to the nature of the key and you cannot switch sharps/flats. If I have a song in C and I want a chord to show as Bb, I cannot do this.
There's been a long discussion already whether this is a bug or a feature.

Your description of the way MobileSheets works is not what I am talking about at all. If a song is in C# or G# or F#, the app should be able to change those keys to Db, Ab, and Gb, respectively. AS far as I can tell, it works. However, see below....

I have a song that changes keys from C to Db on the last chorus. That last chorus refuses to show in Db. It shows C# and refuses to change. I have been talking to Mike via email and he is looking at the problem. We aren't even sure it is a problem, as it could be something about the song file.