Why in everyone's profile appears the tab "About me" and on my profile not?

probably something with your settings just look at your control panel and see if you changed a setting about that

Well, I did. But I didn't find any option about that.

Don't click on User CP.
Instead, click on your name where it says;

"Welcome, Foley.
You last visited: ...... Ago at ......
Private Messages: Unread ..., Total .....
Mood: ......"

Click your name, "Foley".

The first tab is your, "about me"

Yeah I knew that.
But I just wanted to know why the other users who visit my profile can't see.
Thanks anyways.

I visited your profile and saw it.
There doesn't seem to be any problem.

You're welcome by the way.

Go to user cp, profile privacy and check the about me option. By default allows everyone to see it. You may have changed that.

MocroGunz: That's weird because I log into my other account and go to my profile and I can't see, lol.

Pchekinko: All the options are selected as "Everyone".