The bike is a 2018 R1200RT with all the bells and such. Garmin Nav 6. I can't get the average fuel mileage indicator on the appropriate screen to reset. I've turned on fuel management on the Garmin. Instantaneous fuel mileage words, as does miles remaining. The average fuel mileage has read 48.0 mpg for the last 350 miles, even with repeated reset tries. I know this average is too large for my bike. Help me, please.