I changed the pack icon. It's on the far right. The icon is fairly small, though. I feel like it should be larger.

If it's relevant, I'm using a 411 x 412 icon with no transparent textures.

That seems to be around the size of the other icons you have there. The reason it might be looking a bit grainy is probably due your aspect ratio. Try to keep the icon resolution to a power of 2.