Graphs created as a Key Result of an Objective work the same as any graph in MetaPulse. Using the 3-dot menu you can access all features as shown below.
Adding Values & Notes
Click on the Objective
Click on the graph
Hover over the 3-dot menu
Choose Values & Notes
Edit Graph Settings
Click on the Objective
Click on the graph
Hover over the 3-dot menu
Choose Edit Graph
As you can see from the image above, all graph features are available.