No Radius Setting in Controller Configuration Settings

[Haydos04]

Hello, I downloaded the dolphin emulator to play melee on my computer. I've played it and I noticed that i would press the arrow key and the character would move a large distance. I wanted to adjust this so I went on the Internet and discovered that I need to adjust the radius settings, however the controller configuration menu there is no such option. How do I find this? Is this a Glitch? Is my version working (Using 5.0)? Thankyou.