I have just tested it. Search for stations with the < Or > button and select with the Select/Menu button. Then press the presets button 1 or 2 until the confirmation "Saved" appears in the display. Greetings Bruno

I also had the same problem, and the saved volume never worked. Unfortunately, I'm not very patient and got rid of the >device and bought the Sony throws, now everything is OK, operation was very easy.

Set transmitter, long-press to preset 1 or 2, transmitter is saved. Many devices work in this way. I tried this without the operating instructions and it worked.

It is not quite so easy to save the transmitters with the description. But with a lot of patience, I managed to save two transmitters. Don't give up😊