►►How to create default segment for customers?

Seller Admin can see and manage the "All (default)" customer segment from the Segments section.  

All newly created customers automatically will be added to the "All (default)" segment after being Approved.

Sellers can see and fully manage the "All (default)" customer segment from the Segments section.  
Note! The default segments cannot be deleted or the name of the default segments can be edited.   

In more detail read the article What is customer segments?