One Color Heatmaps
One Color Heatmaps are a great way to "dial in" and focus on a single tool. They produce a report based on a single tool and use a single color's varying intensity to represent the clicking activity on your canvas.
When you are showing a single tool, selecting "One color heatmap" should make the image easier to read. With a single color, you'll be able to more clearly see the intensity of areas marked up on the image, because the intensity of the single color is changing throughout it. Make sure to click "Update View" when using this option, and also be aware that it will only allow you to select a single tool when enabled.
As you can see, the heat is represented by a single color. Pulling a one color heatmap of each individual tool is often used by moderators to better understand the individual trends amongst their participants.