Applicants submitting a form without specific routing: each application form has a Route To setting; if that setting is left at the default option (or the form was created before multi-forms existed), applicants from that form are routed to your default program.

Customer Applicants auto-approval: if you have Auto-approve Customer Applicants enabled, applicants who qualify by purchasing with a discount code are routed to your default program (regardless of which form they originally submitted).

Imports without a specific program selected: when importing members in bulk, the import popup defaults to your default program (you can override and pick a different program if needed).

Application form routing dropdown initial state: when creating a new form, the Route To setting initially points to your default program until you change it.

Members can only be in one program at a time, including the default program. Setting a program as default does not move members between programs.

The default program cannot be deleted, since every account must have at least one active program. To delete the program currently set as default, first make a different program the default, then delete the old one.

You can change the default program at any time without affecting existing members or attribution data.