One thing that would be great is a way that the page can be locked into place when zoomed in and using vertical scroll.

When I take notes, I use an A4 page and double click to zoom it in and write. But one thing that annoys me so much is sometimes my hand or arm will touch the page and then the page will be shifted to the left or right.

I propose a small lock button that allows you to lock a page in place, from moving left or right, but still keeps the vertical scroll.