[Zubersoft]

I'm not sure why all of the pages did not zoom, but if you load your song, tap the center of the screen to bring up the song overlay, tap the second icon at the bottom left and then "Zoom/Pan Settings", there is a button to reset the pan and zoom for the current song. You can also assign this as a touch action (a two finger tap does this by default I believe). This will also let you see what pages are changed when you zoom - it should be all pages in current file by default 

Mike