Hmmm I don't really see what you mean, when you go to change your skin to this one are you choosing the Alex player model and not the Steve? When you choose a skin like this with 3 pixel wide arms you have to choose the Alex player model in your Minecraft profile, if you choose the Steve model there will be two black lines that show up on both arms since this skin does not fit the normal 4 pixel wide arms.

She's one of my favorites too, I just love her hero design. I'm really glad you like it ^.^

Thank you! <3