According to the Facebook help centre, if someone has recently changed his/her birthday on
2. Select your name from your news feed. Note that your name can be located at the top left-hand column of the screen.
3. In the page that displays, click About button which is below your cover photo
4. Next, click Contact and Basic Info in the left menu of the new page that once again displayed.
5. Scroll down and hover over Birth Date or Birth Year, and then click Edit to the right of the info you’d like to change.
6. You can then make use of the drop-down menus to change your birthday and use the audience selector to choose who can see it.
7. Finally, hit the Save Changes button.
There are basically two audience selectors next to your birthday. They’re as follows;
1. the one for the day and month and
2. the other is for the year.
Bear in mind that your friends on Facebook won’t be notified about your upcoming birthday if you don’t share the day and month with them.
That is it!
Here’s How I change my birthday and choose who I share it with on Facebook