Can’t position Gradient Texture on Object (eyeball) properly Every time I try to center the light in the middle of the eye like in the tutorial, it doesn't work and ends up centering around where I put the mark seam.
It's supposed to look like this:



But turns out like this:



If anyone knows what's wrong and can help me I'd really appreciate it. Thanks, tutorial's linked below if that helps. 

www.youtube.com/watch?v=E0JyyWeptSA

And here's my blend file:
Your issue is position of UV map.

Tutorial (and you) are using UV texture coordinates, but your UV map is not placed in center of "UV Editor". Since you move the front part of eye in a center it matches.



BTW instead of UV I would rather use Texture Coordinates 

type Generated (Loc -0.5 / -0.5 / -1)



or easier type Object (Loc 0 / 0 / -1)