iPhone Calendar Alert Help
Whether you use the Calendar app on your iPhone by itself or sync it with Google Calendar or another service, you can receive alerts to remind you about upcoming appointments. You can choose to set default alerts on every item you create or alter each listing individually. Any iPhone alerts you set work separately from third-party alerts, such as email alerts from Google Calendar.
1 Setting Specific Alerts
When creating a new event, scroll down and tap "Alert" to set a notification. To change an existing appointment, find the event you want to modify and tap it to open its details. Below the event information you'll see the current alerts set for the item. Tap "Alert" (or "Second Alert") to change how far in advance you want a notification. If the event has no alerts, tap "Edit" and then "Alert."
2 Default Alerts and Alert Types
To set alerts on all future events, open the Settings app and tap "Mail, Contacts, Calendars." Scroll down and tap "Default Alert Times" to set defaults for various types of events. You can also change how alerts appear in the Settings app, under "Notification Center." Tap "Calendar" and pick either "Banners" or "Alerts" to choose between Notification Center banners and pop-up messages.
Information in this article applies to iOS 7. It may vary slightly or significantly in other versions.