Hi, there is a radio manual on the downloads section, it might be for a later model but the instructions might still work.
https://www.fiatforum.com/downloads.php?do=download&downloadid=44
Salient part is:
Manual tuning
1. Press the BAND button [17] to select the band.
2. Press the BAND button [17] for longer than 2 seconds.
3. The message MAN will appear on the display and manual tuning is possible.
4. Press the left /right buttons [18] to tune to the stations. The system will return automatically to automatic tuning after 7 seconds.
Manual station storage
24 stations (6 each in the FM1, FM2, FM3, AM bands) can be stored as follows:
1. Press the BAND button [17] to select the band.
2. Press the left/right buttons [18] to tune to the station to be stored.
3. Press the pre-setting button [12] where to store the station for 2 seconds or more. Note: When storing a station, the station previously stored for that button will be deleted.