Using VEX IQ (1st generation)? See this article.
Step 1: Pair the Controller and Brain.
Ensure that your Controller and Brain are paired. See this article for information on how to pair your (2nd generation) Brain and Controller.
Step 2: Select Settings on the Home Screen.
Step 3: Then, select Calibrate.
Press the X button to navigate back to the Settings screen.
Press the left or right buttons until you see the Calibrate option, and select it by pressing the Check button.
Step 4: Move the Joysticks.
Step 5: Save the Calibration.