The fuel consumption calculation for the EC is set to automatic by default. This setting is noted by the number 1 in the display as you have highlighted. You can set this mode to MANUAL in the Settings screen and the number 2 will show.
Unfortunately, manual calculation mode only lasts until you turn off the ignition. It then resets to AUTO mode. The only way around this is to set the calculation mode to MANUAL every time you start the EC BEFORE engaging drive and moving off. This will take the average from the previous trip and use that as the start figure for calculation. If you leave it at AUTO [1] then it will start from its own preset figure each time.
I have found that the manual mode does work and you can get an accurate fuel consumption figure but having the reset the calculation to MANUAL every time you start, and BEFORE you move off, is a pain in the A...
I've given this practice the flick since and just go with the AUTO. From my reading there is a way to set the process to MANUAL permanently using the Mitsubishi diagnostic tools but convincing a dealer to do this may be nigh on impossible.
I have seen screens of a guy advertising in a Singapore EC forum who does these things for a fee out of hours, probably using the dealers gear, and the screen displayed shows the fuel consumption setting "secret" function amongst other options.