Greetings from Germany!
Wow those are old releases!! I assume you are "stuck" there due to other application requirements/dependencies?
We don't have a command to allow you to do this but there are variius enhancements logged to allow the defaults to be changed via commands.
Whilst we don't normally suggest changing file directly, due to file interdependencies, in this case you could make the change like that.
The file is called ROBOLTIB/RBTCON and the field is RBDLAY.
You would need to "right justify" the number you put in, otherwise it will cause a decmial data error when the System Defaults screen is displayed.
Senior Support Consultant @ HelpSystems Intrnational