Where do I make this change ? Cant seem to find it

Not sure if you found it:

Options --> Video --> Graphics --> Maximum Frames Per Second (second one down)

Go to The Witcher 3 Wild Hunt\bin\platform\pc
Open platformgameplay.ini

There's a configuration option called LeftStickSensitivity. Its default value is 0.7. Changing it to 1.0 makes the movement more responsive. For me it feels good.