Some features require you to press the Top or Home button two or three times in quick succession. Some users may find that they can’t press the button quickly enough to get a response. Fortunately, you can change the speed at which the device will register your presses.
Open Settings and select Accessibility. Choose Top Button or Home Button from the menu.
Finally, choose Slow or Slowest to change the click speed. The selection bar will then flash to indicate the required pressing speed.