Using custom user variables in the API Explorer

Hi there!

I am trying to pre-fill a custom header required for our API.
I have set it in the JWT, and can see it in markdown rendered content using <<myVariable>>.
However I don't know how to set the value in my OAS specification. I've tried setting the example to <<myVariable>>, but that doesn't seem to do anything.

Is what I'm trying to do possible?