"Build settings" and "Environment variables" not accessible in console for Gen 1 App after Gen 2 update

**Describe the content issue**:
Hello, I'm following the linked tutorials to create and access environment secrets at build time. However, some of the key options mentioned are missing in my current Amplify console (e.g. "Hosting"->"Build settings" or "Hosting"->"Environment variables"). I'm wondering if there is an alternative to access and edit the `amplify.yml` (potentially through CLI) to include the environment secrets so they can be accessed at build time.

**URL page where content issue is**:
Amplify hosting - Managing environment secrets
https://docs.aws.amazon.com/amplify/latest/userguide/environment-variables.html#environment-secrets

Amplify hosting - Access environment variables at build time:
https://docs.aws.amazon.com/amplify/latest/userguide/environment-variables.html#access-env-vars