By default, the "Contact Account" is set to "All (Auto)." In this mode, all of your contacts will be shown, and this app will automatically select your primary account to which new contacts will be added. In addition, you can select one of your individual contact accounts such as a local address book, an iCloud account, or an Exchange account in the case that you want to show contacts from one of those accounts only.
Allows you to choose which screen first appears when you open this app
If "Personalize Messages" is turned on, you will be able to send group messages that refer to each recipient by any combination of their first and last names.
By default, this app will use your iPhone's preferred language. However, you can override the language using this setting.
Reset Contact Preferences
Resetting your contact preferences removes any overrides you may have selected for the preferred email or phone number for a given contact when sending group messages or emails.
Best Phone Label & 2nd Best Phone Label
When sending group messages, if a given contact has multiple phone numbers, the "best phone label" determines which phone number will be used to address the recipient.
Best Email Label & 2nd Best Email Label
When sending group emails, if a given contact has multiple email addresses, the "best email label" determines which email address will be used to address the recipient.
Default Email Field
When sending group emails, the "default email field" determines whether the email will be sent using the "to:", "cc:", or "bcc:" field by default.