How to manually change birthdates?

Had a problem when I modified a few things on the join page, I want to reset the date of births for each member manually. Where can I go? thanks

Sorry, nevermind, found it. I dont know why I didnt see it before. Just went to admin and clicked on members, then clicked on their profiles to change it. Alot easier than I expected.

Ok I found a way to do it from within admin, by just going to users, then members and changing it, but it wont save for me. I changed the join page a little and it caused all kinds of problems, so now I want to manually go into the php files or html files and adjust it. Mainly I want to adjust both the age, and the sex of the member, manually. I appreciate anyone that can help me