1. In Formatting Property click on General Property.

2. Enter Following details in Chart Title:
Toggle Enable title
Text: Radar Chart
Font Size: 17
Font Weight: Bold
Color: #d2113f
Align: Left
Background: #4ebeea
Background Opacity: 0.6

3. Fill above details in edit box, As Shown in figure.

4. Click on Preview and Save and Exit.

5. Now, match your Radar chart with the below example, it should look like the figure below: