A Human-Machine Interface (HMI) system comprises a machine interface, a processing system, and a user interface. The machine interface receives operational data associated with an operation of a machine. The processing system processes the operational data associated with the operation of the machine to determine a trend in the operational data. The user interface displays a graphical representation of the trend, and receives a first user input and a second user input simultaneously on a surface of the user interface. The processing system processes the first user input and the second user input to determine a change in the trend. The user interface displays a graphical representation of the change in the trend.