Settting Environment Variables through Vars on ShinyApps.io

Hi All- I have an app hosted on ShinyApps.io. I would like to set some environment variables through the {x} vars interface as I have done using RStudio Connect on other servers. However, I don't seem to be able to access this option on my app hosted on ShinyApps.io. Can anyone point me in the right direction?

Thank you,

Mike