Hello Drskmishra
To rename a thread that you have started;
While signed in, go to the first post of your thread and click the ‘Edit’ button.
Next, click; ‘Go Advanced’ to bring up the extended post editor.
Above the main body of your text is an area marked, ‘Title:’, containing an editable text box with your threads current title. You can enter a new title for your thread here.
When done you can click the ‘Preview Changes’ button to see how it will look and when happy click the ‘Save Changes’ button.