A guy on the ED forums was kind enough to give me a list of all the cloud presets and their individual settings. I am fairly certain that the numbers are base/tops and the abreviations are SCT = scattered, BKN = broken, OVC = overcast, FEW means just that, a few clouds and LYR = layer.
So, when you choose one of these presets, you get an elevation slider just below the picture representing the preset, which you can use to adjust the whole preset up or down and the interval or elevation gaps between layers remain the same.