Unfortunately, that range is set in the code and is not configurable. The range of the signal is given between -100 and 0 and we break that up into chunks and assign one of the icons to that range. Apparently your device is sending back what we are interpretting as a moderate signal as a high signal.
What device are you using? I can be sure to try and test against a similar device if we have one in our lab for the next wireless release.