To edit the user creation defaults you can use the Connection tab on the General page of KUser's configuration dialog, which is accessible via the menu Settings → Configure KUser. There you may change the defaults that are used when creating a new user: Shell and Home Folder (or home folders volume). You can choose whether to make a home folder on “create” or not, and to copy a skeleton (standard configuration files) to the home folder or not. You can also enable User private group mechanism, which creates a new personal group with the creation of a new user, and removes the personal group when the user is removed.