Question: I want to change my default lookup entity from Account to Contact
Answer: This is possible out of box.
- Download the OrgDB setting tool from codeplex: https://orgdborgsettings.codeplex.com/
- Import the “OrganizationSettingEditor” solution
- Change the vale for SetRegardingLookupDefaultEntityType OrgDBSetting to contact.
- Refresh the URL.
- Now go to Appointment / Phone call and choose the lookup. It will take you to contact as default lookup type.