After you enroll your Wi-Fi devices into the app you can easily change the order. Start by clicking on a room. If you have chosen not to use rooms, click on Unassigned Devices.
In the Room Details screen press REORDER just below the room name.
Use the ≡ icon on the right to move lights up and down. When done press DONE.
If you wish to change the order of the rooms within a residence, please see the article:
How Do I Change the Order Of Rooms In My Residence?