Some features require you to press the Home button or Side 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. Depending on the type of iPhone you have, choose either Home Button or Side Button from the menu.
Choose Slow or Slowest to change the click speed. The iPhone will then vibrate to indicate the required pressing speed.