ArduRover speed control

I am new to the world of drones. I am building a UGV and I have flashed the latest ardurover code on my pixhawk 4 flight controller. I have gotten the manual mode to work using 4 channel flyky transmitter and receiver and it works fine. I intend to use the vehicle for indoor purposes and I am testing the guided mode using dronekit examples. However, the speeds are far too high for me to conduct the tests. I am changing the groundspeed variable, but it does not effect. Is there something I am missing. Any help is appreciated.