The Zoom function is only accessible through the three icons in the icon bar at the top of your Symmetry screen, or through the corresponding shortcut on the left of your main screen.
After having zoomed in one or several times, you can return to the previous zoom state by clicking on the Previous Zoom State icon.
When selecting the Zoom In icon, you can select a specific area in your job screen by clicking opposite corners of the area you want to view. Any combination of corners (top left and bottom right, top right and bottom left, etc.) will work.
There is a single zoom shortcut available, which will work differently, depending whether you selected a single text line or not.
With a text line selected, clicking the zoom shortcut will have Symmetry zoom in onto the text line in question.
Clicking the zoom shortcut will have Symmetry zoom out to the entire job.