I think you misunderstand what catdepth means. It is going to display levels beneath levels. It is not a setting to say how many cats to display. It is going to display all in that one level and then go to the next level.
I hope that clarifies the confusion and as my reply above states there is nothing
The only top level setting I noted is in the index options and thus looking at your site which we can not do since you have it blocked to viewing I cant suggest anything else. I am assuming what you have is a couple top level cats and many subcats but you would need to make your site viewable to us