There are 3 sets of presents for XM1, XM2, XM3. You need to set 6 stations into each set of presets. When you press the XM button it will go to the current set and show the current station playing. You need to touch on the screen the MENU icon, then PRESET LIST to see all 6 channels for that set. You can also use the ENTER button the left side of the steering wheel when MENU is highlighted and when PRESET LIST is highlighted.
In actuality, the presets are specific to each key fob, so my wife has her set of 18 stations linked to her keyfob, and I have my set of 18 stations on my keyfob, but we do have a few stations that overlap but are different locations in the presets. For example, she sets a station to XM2 #3 and I have the same station on XM1 #6.
I believe it's the same deal with the presets for AM, FM1, and FM2 being linked to each keyfob.