Sites / Sections is a sophisticated way to control the global account settings, regardless of the number of web sites in use. As of version 9.5, some features and modules will look to this section unless specially assigned to look elsewhere.
When Editing a global setting, there are currently 15 tabs: Main, Email,Reports, Google, Invoicing, Customer Service, Inventory, SHipping, Default G/L Accounts, Acct Receivable, Acct Payable, Purchase Order, Production Order, Synergy Integration, and Security.