I have tried to register in some forums, but there was a message that words are not typed coorectly, or the answer of a question which is always wrong, why they do that

Sounds like a CAPTCHA failure. You should be able to refresh the images to get something you can easily recognize. CAPTCHAs are used to restrict registration to actual humans and reject bots.

That's either sweet or creepy.

That's either sweet or creepy.

What makes the difference for the OR clause? ;)

Who the poster is.

when you regesiter in the forum there are some cases involve like upper case letter or small case letter

this is not the big matter every forum have their own rules in which you can get register