Open TikTok and go to your profile
Tap the menu icon in the top right
Tap Settings and privacy
Tap Account
Tap Personal information
Tap Birthday if it is available
Update your birth date and save the changes
If Birthday is not editable, go to Report a problem in Settings and privacy
Select Account and profile
Select Editing profile
Select Other
Tap Need more help
Request a birthday correction and provide the required proof of age if asked