For settings (defaults and references), the command is implicit and is always an add. You must specify a parameter option with the help of the keywords reference or default to specify what you want to define. If the option is a reference, you must provide its name. Else you need to specify if the default is for sut (system-under-tests) or assert with the help of corresponding keywords. Then you need to specify which feature of the setting will be added. Only connectionString has been tested but others should work. Then finally, you need to specify the value that you want to set.