How to filter the dashboard by depot?

From the desktop click the filter icon underneath your name –

This will allow you to select a specific depot to view in the dashboard. Your depots will appear from the drop-down list. Click to choose the appropriate selection –

 The dashboard will now only show dashboard information for that specific depot. 

To change the display/filter back to all data, select the filter icon again and click display all data. The dashboard will then revert to show all data for your company to include all depots.