All lists in WinDirStat can be sorted at will. The current sorting is indicated by the symbols < and > in the column headings. < means ascending sort, > means descending sort.
You can set the desired sorting by a mouse click on a column heading.
Actually two columns are drawn on the sorting. First that one, on which you clicked last, and second - if the elements are equal regarding this column - that, which sorted before.
Note that the sorting of the directory list of course respects the tree structure: sorting occurs only within one level.
The column widths and column order can be adjusted via drag 'n drop. The widths and column order are persistent; that is, at program start they are automatically restored as you have set them last.