If I want to highlight something somewhere in the middle of the video track, highlighting ONLY that region to be rendered, it is not doing that, t just keeps rendering back at the beginning of the project.
Is there something I need to check in preferences?
Look in the rendering options for 'Render loop region only' or words to that effect. It depends upon which version of Movie Studio you're using where the option is. Check the help and you should find it.