Hello,
Here is the video on how to programme the Dxe radio.
https://www.youtube.com/watch?v=BmEsvDrIFag
For the Apprentice S, the SAFE button is on Ch 5. If you need to reverse the trainer button, you need to reverse the Ch 5. (refer to the YouTube channel on how to do it thru the radio).
For buddy box both Dxe, you need to perform the following