Here you can customize the device specific reports to be shown in Device Tree and the Reports page.
For each of the selected device, you are provided with the option of selecting from the default Available Reports the most required list of reports and move it to the Selected Reports. And only these selected reports would be listed in the Device Tree and the Reports page for this device.
The report view customization for the selected device can be applied on the selected device alone by clicking Apply for Selected Device. And, if you would like the report view customization for the selected device to applied for all other devices too then click Apply for All Device.