Several tools are available to change the appointment times.
1) You can change the appointment time by double clicking on the appointment. The appointment screen will appear. Change the time on the appointment screen and save & close the appointment.
2) You can also drag the bottom section of the appointment to the ending time desired.
Follow these steps:
Click on the highlight line on the bottom of the appointment (the cursor will change to a Double Ended Arrow line) and hold down the mouse button. Drag the mouse up or down to change the ending time.