To access individual remotes for each device in the profile, touch the remote icon in the lower right of an activity. Device remotes are similar in appearance to activity remotes but by default all the buttons relate just to the selected device. You can change the device by swiping the device name in either direction.
When in a device remote a touch on the remote icon in the lower right brings up a complete scrollable list of all commands for the device. Handy for testing commands before customizing buttons. Touch the X to return to the previous screen.
These remote screens can be customized in the same way as the Activity screens:
Squid Eye/Advanced/Customize button/long touch on the button to edit.