Not sure which model year you own. 2014 owner's manual, page 5-29:
Preset channel tuning
The 6 preset channels can be used to store 6 AM and 12 FM stations.
1. To set a channel first select AM, FM1, or FM2. Tune to the desired station.
2. Depress a channel preset button for about 2 seconds until a beep is heard. The preset channel number or station frequency will be displayed. The station is now held in the memory.
3. Repeat this operation for the other stations and bands you want to store. To tune one in the memory, select AM, FM1, or FM2 and then press its channel preset button. The station frequency or the channel number will be displayed.