Where can an app builder edit an existing app to add components to the utility...

To add components to the utility bar of an existing app:

C. App Manager. This is where Salesforce apps are configured, including the utility bar which can house components like a chat tool, recent items list, or custom Lightning components.

Steps to edit an app's utility bar:

Navigate to Setup → App Manager.

Locate the desired app and click on the dropdown next to it → select Edit.

In the App Builder, navigate to the Utility Items tab.

Click 'Add' to include new components to the utility bar.

Configure the properties of the utility item as needed.

Save the app configuration.

For step-by-step instructions on modifying apps, see Salesforce's guide on Managing Apps in Lightning Experience.