The 'Reorder' function was created to change the order of the rooms on the home screen.
In the Menu - Rooms, simply hold your finger for a few seconds on the room you wish to move and drag it to the desired position.
The change will take effect on the home page and on all screens where rooms are listed.
It is not possible, however, to change the order of the devices, which are shown in the order in which they were associated.