How can I change a category mismatched post?

You need to request the forum moderator or administrators to do that for you. You can see moderator name on index.

OK , thanks for the reply.But as editing is possible why should it also be included in it?

Changing category is admin/managing feature and cannot be done by others.

But I don't understand why a thread started by a member can't be changed by himself?

It is due to the security reasons.

It is due to the security reasons.

So it is a right decission.Let it be so for ever.

While writing a post, utmost care should be exercised to see that there are no errors of classification, spelling etc. Already there is possibility of editing the contents including title. This is sufficient. If the category mismatches, there is nothing to worry as long as post clearly explains author's views. Let the moderators and management change the category if they think so appropriate.