Please check the following settings.
- Default notification settings: If a notification time is set for "Timed Notifications" or "All-Day Notifications" under "Calendar Settings" → "Reminder Settings" in the settings screen, every new event gets a notification automatically. If you don't want notifications, open each of them and remove all checkmarks (so that nothing is selected)
- Daily Summary: If "Remind All Events for the Day" is turned on in the same "Reminder Settings", a list of your events is sent in the morning of the day or the night before. Turn it off if you don't need it
- Notifications from Google Calendar: If you use events from Google Calendar, a notification time may be set in Google Calendar, and those notifications may arrive separately from this app's notifications. We're sorry for the trouble, but please sign in to the Google Calendar website or use the Google Calendar app to change the setting there