To change modes using the Elecraft K2 and K3 you must cycle through the available modes. KComm provides a set of instant band change buttons that allow you to instantly select the mode you wish to use.
Some of the mode buttons may be disabled depending on the modes supported by the Elecraft transceiver. However, KComm assumes that all the possible modes are available, so if you have a K3 the FM button will be enabled even if you have not installed the FM filter.
The DATA button opens a drop-down menu that displays a selection of modes that depends on how they are being generated. If you are operating under Windows and using the PSK Core DLL then only PSK31, PSK63 and PSK125 will be available. RTTY will not be available because the DLL does not support it.
If you are using the Elecraft K3 DSP then RTTY and PSK31 will be available but not PSK63 or PSK125, because the K3 does not natively support higher speed PSK encoding or decoding.
If you are using Fldigi then the most popular modes supported by that program will be shown.