Where the zoom is available
You can to change the time scale (zoom in/out) on all the following schedule views:
- When view of a project
- Who view of a project
- Schedule view in multi-projects
- Gantt view in multi-projects
- Calendars view in multi-projects
How the zoom works
To do so, click on the “Zoom” icons 
at the bottom right of each view mentioned above to zoom in or out.
You can also select the desired level by directly by adjusting the cursor or by positioning it directly on the displayed indicators (W: week, D: day, ½ D: half-day, 4H: four hours, H: hour) 
Note: The zoom level is maintained when you return to the view in question.