On the right hand side underneath Automatic inactivation for performances you should see Public volunteer sign up (pictured above). Toggle the 'Display a link on your public events page to recruit new volunteers' to 'Yes'. You also have the option to attach a survey to the volunteer sign up process.
We've included a direct sign up link as well so that you can use the URL for your own website, in emails or social media.
Once enabled the volunteer link will be at the bottom of your ThunderTix page (pictured below).