I think having the key / time signature "stick" makes a lot of sense... I will work on that. The only thing to look out for is key signature / time signature changes, and make sure those get captured too and that they stick...
As for scrolling, it seems like that is a feature that some people might prefer. I will most likely add that as a feature to it.
I think having the page stay still for the majority of the time (like it is now) is better than to have it constantly moving, but when you do change pages, scroll to the new position (ease-in, maybe ease-out too).
Removes the disorienting jolt of having everything just change, but also not always moving and being a distraction
As for scrolling, it seems like that is a feature that some people might prefer. I will most likely add that as a feature to it.
Thanks!