Changing the auto-hibernate settings on a AWS Cloud9 EC2 Instance

This may have changed since the previous answer. I was looking for exactly this, and didn't see any Preferences Tab in the main Cloud9 page. But I did find it in the project settings->EC2 Instance

On an EC2 environment, go to AWS Cloud9 > Preferences > (in the Preferences tab) Project Settings > scroll down to Stop my environment (or click EC2 Instance in Project Settings section on the sidebar)