I noticed some posts about how to switch from stable to unstable. This is my method at the moment, not sure if I am able to specify in configuration.nix which package uses which channel, I know nix-env isnt the most popular, but it works for me for now.
I feel like you shouldn't submit screenshots for this type of stuff and instead format it as a post (to facilitate copy/paste and also because this isn't Instagram), but maybe I'm just being overly picky.