This obviously requires an iPhone with a 3D Touch display, whether that’s an iPhone 6s or iPhone 6s Plus, other models will not have this setting available:
1 Open the Settings app in iOS and go to “General” then to “Accessibility”
2 Go to “3D Touch” and locate the “3D Touch Sensitivity” portion of the settings, the slider below this is what you’ll want to change to fit your preferences, pick one of the following:
•Light – a soft amount of screen pressure activates 3D Touch peak, and a slightly more firm amount of pressure activates 3D Touch pop
•Medium – the default level of pressure sensitivity for 3D Touch displays
•Firm – a notably harder amount of screen pressure is required to activate 3D Touch peak and pop
If you find yourself activating 3D Touch when you don’t always want to, you’ll probably want to use the “Firm” option, whereas if you find the required pressure is too great, using the “Light” feature is ideal.
This is really largely a matter of personal preference, but it also depends on what you’re using to activate the touch screen, if you use a case on the iPhone, and your general usage patterns, and whether or not you use a finger, toe, stylus, or other pointing device.
My personal preference is for the “Light” setting but when demonstrating the feature to a friend they found it way too easy to activate, so they strongly preferred the Firm setting. Try it out yourself and see what works for you, you can always make another change again by returning to 3D Touch settings