3D Touch makes it easy to quickly pull up four of your favourite contacts from your iPhone's home screen, but the four that appear there might not be your most contacted people. How-To Geek shows off how to change that.
The four that appear in the 3D Touch widget are the top four people in your favourites list, so to change who's there, you just need to edit the order of your favourites. Head to Phone > Favourites, tap the Edit button, then tap and drag the contacts around to reorder them. You can also change which phone number appears if they have multiple, or even select Messages instead of a phone call.
How to Customise 3D Touch Shortcuts on iPhone [How-To Geek]