For Android Users
Within "Me" tab, scroll down and find "Data & Settings"
Go to "Profile", and you will find the "Step Length" below "Height"
For iPhone 4, 4s, 5, 5c users
Within "Me" tab, scroll down and find "Settings"
You will find the "Step Length" under your personal profile
*For iPhone 5s, 6, 6 plus, 6s, 6s plus, which equipped build-in motion coprocessor, the coprocessor will measure your step length and adjust itself, so the manually adjust step length function is no longer required on these devices.