I want to assign the value of one variable to another (no scripts please). I have tried assigning a collection variable to another variable in the same collection and I have tried assigning an environment variable to a collection variable and neither seems to work.
In the following examples there are three variables SuperToken, UserToken, and api-token.
What I want to do is to use the value of api-token in my requests and change it for all requests by assigning either SuperToken or UserToken on the variables tab of the collection.
In my first screenshot you can see the variables tab of a collection. Typing {{ into the Initial value field of the definition of api-token does not bring up the variable selection popup. If I type {{SuperToken}} into that field the value of api-token becomes the literal string “{{SuperToken}}”. Not what I want! I want a variable value assignment.
I have also tried creating SuperToken and UserToken as environment variables with the same result.
Variable substitution is working within requests. My next screenshot shows what happens when I type {{ in the value field of a request. The value of api-token is the literal string “{{SuperToken}}” showing that no value assignment was done where api-token was defined on the collections.variables tab.
The strange thing is that I thought I had this working once but it has stopped working and I can’t figure out why. Maybe it never worked and I’m just imagining things. 
Is this a bug? The documentation says
“You can use double curly braces to reference variables throughout Postman.”
However, later it says
“You can use variables in request URLs, parameters, headers, authorization, body, and header presets.”
So maybe what I want to do is not supported. If not then I would submit it as a feature request.
Thanks for reading.