Single Zoom Mode
Single Zoom mode returns you to the previously selected tool after a zoom has been performed.
For example, when using the Smart Tool you can click the Single Zoomer tool, and once the Zoom operation has been performed, Pro Tools automatically switches back to the Smart Tool.
To use Single Zoom mode, do one of the following:

Click the Zoomer tool pop-up menu and select Single Zoom mode.

Right-click on any track and select
Tools > Zoomer Tools > Single Zoom.

Press the F5 key to toggle to Single Zoom mode.
Single Zoom is identified with an arrow to the right of the Zoomer icon.
Single Zoom mode
Normal Zoom mode does not have the arrow.