Sounds like you know how to operate the cruise control except that it's not operating properly. Everything you have tried sounds correct. All I have to do to change to a new speed is disengage either by applying the brake, flipping off the power switch, or turning on the Jake. When I re-engage the cruise control it can be set to any speed I wish. I can also reduce the set speed while using the cruise by pushing the center push-button. Each push reduces the set speed by 1 mph.