To edit PSA custom settings, from Setup, click Develop | Custom Settings. For further information about modifying custom settings, see the Salesforce Help.
To edit a PSA configuration setting in a configuration groupA collection of configuration options contained in the configuration groups tab that defines behaviour of a FinancialForce PSA object or feature.:
Concept Information
Setting up Accounts and Opportunities
Managing Profiles, Security and Sharing
About Time Periods, Work Calendars and Holidays
Reference Materials