Put your screen into radio mode and then press and hold down the "SELECT" button. You should see a message "PRES OFF" appear. This will have now toggled your steering wheel buttons to go to the next strongest station instead of your next pre-set. To go back to the way it is now, repeat the procedure and you'll see the display read "PRES ON".
Also, if you are in the mode where the buttons are set to go to your next preset, if you hold down the up/down steering wheel buttons for longer then a second then it will scan to the next station rather then going to your next preset.
-UCrewX5

Also, in addition to UcrewX5 suggestion re: scanning for radio station, you can switch to FM AUTOSTORE mode....hit FM button on your radio/NAV from FM 1-->FM 2-->FMA.....Once you are in FMA (Autostore)....hold the FM button for 2-3 seconds and you'll see the radio search for the 6 strongest station in the current area....Then you'll have 6 preset stations you can rotate through.....If you don't like your current selection or need to find another set....just hold the FM button again and find more stations.
Kewl X5