Priority Inbox Checkmark to make Priority Inbox your default inbox for this account.
Signature Allows you to add a signature or other information to outgoing email.
Confirm actions Allows you to choose which actions will display a dialog box asking you to confirm whenever you want to archive, delete, or send a message.
Reply all Checkmark this setting to make ‘Reply all’ the default action for responding to messages.
Auto-advance Allows you to choose which screen to display after you delete or archive a conversation.
Message text size Allows you choose the size of the text in a message for easier viewing.
Batch operations Checkmark this setting to allow batch operations.
Sync inboxes and labels Allows you to manage which conversations are synchronized and how often.