when using LT browser, adding new device - can you somewhere edit custom devices? and 2) what difference does it make when you add device i.e. 1920 x 1080 as desktop or as mobile?
The first question, you cannot edit custom devices. You would need to delete and then create it again
For the second question, you would see a difference in the way they zoom. Mobile devices will be zoomed fully whereas in desktop devices only the viewport will zoom. Also, you would get different thumbnails for both You could rotate a mobile device but won’t be able to rotate a desktop device.