KingComposer Template override not working

Hello
I want to override testimonials element layout.
I have followed following guide http://blog.kingcomposer.com/overwrite-an-element-of-kingcomposer-page-builder/

I have created a new file name kc_testimonials.php under directory wp-content/themes/myChildTheme/kingcomposer/ and then copied contents from wp-content/plugins/kingcomposer/shortcodes/kc_testimonials.php and then tried changing the layout of element but it is not working.

I have tested the element layout by emptying the newly created file inside theme folder but nothing happens.

If i change something in plugin core file then it works fine.

Can you please tell me where i am doing mistake.

Thank You