Ultragauge Speedometer Adjustment

I can't get the ultragauge to adjust the speed with new tires. I have followed the directions to a T and can't get it to work. Can anyone provide advice or have a similar issue?

 

The Ultraguage doesn't need a speedo calibrator installed? I'm not familiar with the UG but since the dash is electronic, who knows.

 

You'd think it would be that simple, lol but no it does. They have instructions on their manual but it doesn't do anything. I'm still going about 4-5 mph over what it says. If I can't figure it out I'll probably sell it. I mainly bought it for that tool. All of the other gauges are cool but don't fully understand how to work them.