From the Quality Control screen, you can Validate or Invalidate any of your gated leads. To have leads move from a Lead Source to Quality Control, you will need to enable Quality Control from the Lead Source setup screen. You can read more about enabling this feature by reading the Lead Sources - Implementing Quality Control article.

As with any of the main screens that contain leads, you have the Choose Column feature, that allows you to add Columns, then you can drag them into the desired layout.