on my EDC 120, when I access the 120 lumen mode, I have to keep the button depressed or it will go back to the lower output mode.
FROM OFF:
1. CLICK (a quick press and release) to turn the light on, and then quickly (within a 1/3 of a second, or so)...
2. PRESS and HOLD until the MAX/HIGH output mode comes on (maybe 0.5sec). NOW, the MAX output mode will be LATCHED ON and you can release the tail-cap switch/button.
FROM ON (any mode):
1. CLICK (a quick press and release) to turn the light OFF, and then quickly (within a 1/3 of a second, or so)...
2. PRESS and HOLD and the light will immediately turn back on to its PRIMARY setting (if it doesn't, then you didn't PRESS it fast enough after clicking it OFF in step ONE), continue to HOLD it PRESSED until the MAX/HIGH output mode comes on (maybe 0.5sec). NOW, the MAX output mode will be LATCHED ON and you can release the tail-cap switch/button.
hope this helps. if my instructions are NOT clear, please Post back and i'll try to clarify them.