To edit a metric label on your chart, open Visible and navigate to the dashboard where your chart lives. Locate the chart you want to rename the metric of. Click the three horizontal dots in the top right of the chart and click Edit. When you are in the chart editor, select the Edit label pencil button on the right side of the metric panel.

Edit the metric name in highlighted area below. Click the checkmark button when finished.

Now, you will have the metric label changed on the right-hand panel and the legend name changed as well.

Please let us know if you have any additional questions!