You may use keyboard shortcuts to activate many of the annotation and navigation tools.
These include the following:
b - activate pencil tool.
n - activate note tool.
a - activate arrow tool.
t - activate the text highlight tool.
h - activate hand (pan) tool (or hold Shift key to temporarily activate it until released).
i - Open/close metadata panel.
z - activate zoom tool (or hold Option key to temporarily activate it until released).
0 - zoom fit all.
1 - zoom to actual size.
2 - zoom to 2x.
3 - zoom to 3x.
9 - zoom fit width.
space bar - start / pause video.
left / right arrows - advance to next / previous frame in video (or page for PDF files).
up / down arrows - advance to next / previous file in review.
x - toggles the mouse wheel action between vertical scroll and zoom. You can also press and drag the mouse wheel to pan.