Samsung
Turn On Birthday Reminders in the Calendar auf Samsung
Samsung Calendar pulls birthdays directly from your saved contacts and shows them on the matching date. By default, this entry behaves like a static note: no push notification, no lock screen alert, nothing that flags an approaching birthday.
This happens because birthday reminders are controlled by a separate alert setting, not by the general calendar notification toggle. Even if your regular event alerts are switched on, birthdays stay muted until you enable them on their own.
Where to turn it on
Open the Calendar app and go to Tap on Calendar ➔ Open the Menu ➔ Tap on Settings ➔ Tap on Alert settings ➔ Tap on Contact´s birthdays. From there, Choose an option to set when you want to be notified, for example on the day or a day in advance.
Turning this off again works the same way: return to the same menu and pick the option that disables the alert. If a specific birthday still does not show up, check that the date is actually saved in the contact entry, since Calendar only displays what the Contacts app provides.