The Steer / Drift Button Display option in the Settings menu allows you to show or hide the Steer (or Drift) button during races.
When this option is enabled, the Steer button (if Manual Drift is enabled) or Drift button (if Manual Drift is disabled) will be displayed on the screen during races and can be swiped to perform the corresponding action.
When this option is disabled, steering cannot be performed by swiping the screen if Manual Drift is enabled (since that action will perform a drift instead), and drifting cannot be performed by swiping the screen if Manual Drift is disabled (since that action will steer instead). However, steering can still be performed though the use of Gyro Handling.