One more thought: if you wear prescription glasses that have the auto darkening lens, they will also darken when your welding, kinda gives you a double darkening.
I wear transition lenses and the effect is minimal - there is not enough UV light passing through the helmet lense to make them change.
Seeing the arc is something that takes a bit of practice believe it or not. As stated above, make sure the helmet is working - although if it wasn't you'd be going blind as opposed to not seeing the arc.
As stated, set to 10 or 11 (10 can be hard on the eyes if you're welding for a long time).
Next, you should be tilted off to the side slightly so you can see the path the weld will take. Next, you want to be at least 12" away from the weld - too close also contributes to the problem. Focus on the puddle, not the flash - this is what takes practice. There may be too much light getting behind the helmet and that can throw you off - try taking a shop rag to the helmet and throwing it back over your head to keep shop light out. If that works, buy a proper flame-proof hood.
