Hello,
As it was stated above, you will have to make a support ticket for your age to be changed. You can open one here:
https://manacube.com/support/
Make sure to include the date that you want it changed to so it is easier for us to sort that out.
If you have any concerns or questions, do not hesitate and contact me via Discord, my name is
fau#1734. Or start a conversation with me on the forums.
Best Regards,
Faudon