How to create reference to global variables from environment variables?

My question: How to create reference to global variables from environment variables?

Details (like screenshots):
I type {{ in the environment variable section for the initial value section and there is no drop down to pick a variable (such as globals).

How I found the problem:
In my case I have different base API urls like:
https://mydata.com
https://dev-mydata.com
https://test-mydata.com

And I have different authentication accounts like:
username: John
password: sql395

username: Sam
password: React458

I don’t want to repeat these more than once, but at the same time I want an environment for each user to each base API url. So I want environments like:
John Prod
John Dev
John Test
Sam Prod
Sam Dev
Sam Test

So if I make a global variable for each url and credential, then I was thinking of just making an environment for each of the above and reference the global variables for each url and credential combination.

I’ve already tried:
Typing {{ on the initial value field.