What action is needed to edit a template once it has been placed on the diagram?

To edit a template that has already been placed on the diagram, highlighting the template is the necessary action. When you highlight a template, it allows you to access the editing options specifically designed for that template. This can include adjusting its properties, changing its layout, or modifying any other relevant settings.

This action is crucial because simply clicking the template icon again does not inherently indicate that you want to edit that specific instance of the template. Accessing the global settings is more about overarching adjustments that affect multiple templates rather than editing individual ones. Removing and re-adding the template is inefficient and unnecessary when you can simply highlight it and make the desired changes directly. Thus, highlighting provides a straightforward and efficient path to modification.