In the left menu, “Devices” then “My Devices”, you can see the information of your trackers (device and/or smartphone).

 

To change the name of your device, click on the icon on the right side of your screen, in the insert corresponding to your device. 

 

To change the picture of your device, click on the icon on the left side of your screen, in the insert corresponding to your device. 
You can then upload the photo of your choice, within a limit of 2Mo, with the icon