How to set up your own scalability settings/groups that "overwrite" the default one's?

I am interested in getting this done by editing an “ini” config file, to create my own scalability setting groups, to “overwrite” the default ones.
But whatever file I edited, there were no changes in testing.

How can it be done exactly?
What file exactly do I need to edit? And how are the correct edits done?

I would be very grateful with any help on said subject, thanks in advance.