The basic NON-Platinum version of Vegas Movie Studio 16 does not allow for customization of rendering templates.
It never has, as far as I am aware.
You need to upgrade to Vegas Movie Studio Platinum 17, if you want to access full customization controls.
Remember to turn everything off at least once a week, including your brain, then sit somewhere quiet and just chill out.
Unplugging is the best way to find solutions to your problems. If you would like to share some love, post a customer testimonial or make a donation.