Is there any way to change the name of a thread when its already been posted or do u have to make a whole new thread?

Go to the thread you have created, click "edit", then click "go advanced". There should be the description of your thread and the title. Simply edit the title.
This also works with posts.
Hope this helped!

Yeh ive done this but it when i look back it still has the old name

Odd. You may only be able to change the name that is shown when the thread is open. There may not be a way to actually edit the original title. Let me try to test it in offtopic.

EDIT: Worked for me in off-topic.

Try editing the title of this thread.

Works now but before in the market thread it didnt work wierd
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It works on this thread but not on market threads

Very Very Odd. I suggest posting it as bug in General Reports.

Good day to you Sir c:

Yeh ill post in general reports