Default insert sites for users
In the Users application, you assign users to a default insert site to insert records. The records that users view pertain only to the default insert site. Without a default insert site, some applications cannot function. For example, without a default insert site, users cannot add purchase orders in a site-level application.
For site-level records, the site defaults to the value of the default insert site. For organization-level records, the organization defaults to the organization of the site that is specified as the default insert site. The Profile link in the navigation bar enables users to change their default insert site.
The Use Default Insert Site as a Display Filter setting is a filter that allows users to view only records from their default insert site. However, if the application is at the organizational level, this setting allows users to view all records from all sites within the organization. If you do not use this setting, users can view records for all the sites to which they have access.