First off see Mark's great video on the 210EXT panel.

But if you don't have 10 minutes or just want to print and tape this to the welder (edit whatever).

Press and hold the amp knob for 4-5 second until you see D01 on the display. Turn to the DXX setting and push to change each setting below. Two pushed to exit back to the main menu.

D01= N/A
D02= HF Arc start duration (.5-5 seconds)
D03= HF Arc start frequency (10-100Hz)
D04= HF Arc start amps DC (10-100 amps)
D05= HF Arc start amps AC (15-100 amps)
D06= N/A
D07= Lift start current DC and AC (10-100 amps)
D08= Torch trigger or amp control 4T function by type torch (00 = 4T 01 = 4T Normal)
D09= Voltage Reduction Device for MMA/stick (00 = VRD off 01 = VRD on)
D10= Pulse mode Standard or Advanced. AC is added to DC in Advanced mode (00 = Standard 01 = Advanced)