I'm guessing,,Shade 9 is the lightest shade and should be the one you are using,,,the shade doesn't affect sensitivity,,,the sensors take in the light and the sense setting does that,, trouble seeing where to weld,,perhaps you are too far from the weld and need to get your face closer to the action,,,or need a cheater lense to magnify the weld,, I use one my self...using a soapstone line can also help guide you,,,you age the condition of your eyes the type of welding MIG,,TIG,,or stick can decide the proper shade to use...if you have a buddy with some welding experience let him try the new helemet,,,it could be a dud,,then again he may give you some pointers as how to follow the line you need to weld..One of the things that really makes a difference when welding indoors is to have the weld area well lighted,,if the room is dark you will have trouble to see it clearly when you weld,,,,use a trouble lamp to light the thing being welded and then try welding...makes a difference...