3D Touch is a new, highly sensitive reaction to how much pressure you apply to apps on your iPhone. It reacts immediately, while also allowing different “levels” of actions based on how firmly you press. If you have problems with the sensitivity of 3D Touch, you can change it. Go into Settings > General > Accessibility > 3D Touch. Move the guide from light to firm to get your personal setting. There is a sample image there so you can test the setting to meet your personal needs.