The 370 indicator does not tell you when to change, simply shows the gear you are in the display all the time. As Dan says, blanking out the display by some black tape might be the only option - can't recall if there is another way to stop it.
New models have small up and down arrows next to what gear you are in, to let you know to change for economy etc.
To OP - I think I read somewhere that the arrows cannot be turned off