GGU-3D-SSFLOW: "Default soil column" menu item
The default soil column defined in this dialog box is assigned to all new FEM elements defined using the "Mesh(x/y)/Automatic" menu item.

If you edit the given soil numbers and leave the dialog box using "Done" the newly defined soil column will be adopted as of this moment for newly defined elements. If elements are already defined, they can also be retroactively assigned this soil column using the "For all" button.