To set thresholds values and colors for indicators that support it, hover with the mouse over the indicator, click on the Widget Properties button and navigate to Preferences.

 

In the Threshold tab, you can define ranges and colors for the thresholds.  Click OK to save.

Component	Description
1	Set indicator boundaries automatically based on the current value
2	Set indicator boundaries manually by providing start and end values
3	Define the number of ranges
4	The value multiplier is used to shorten the numbers shown on a scale
5	Add/Remove a range
6	The currently configured ranges
7	The range start value
8	The range end value
9	The range color
10	Use gradient colors for the range, starting and ending at specified colors