I have a photo a mine (MEP-016D yanmar diesel retrofitted MEP-016c, but is the same control box), but it was done with a phone camera and is not clear enough to read the fine print markings. The left one is 6 position selects voltage Line to Line and Line to Neutral for the voltage meter, the right one is 3 position selects the same for the current/amp meter (I assume L-1/L-2, L2/L3 and L3/L1, although I guess it could be L1,L2,or L3 to neutral). Hope this helps some, I have to get going before daylight today, but can take a better photo this weekend if you still need it. Either way it is just an instrumentation selection, and does not change the function of the generator
Ike