I tried using the Toggle mark occurrences (Alt + Shift + O) button and also in Preferences -> General -> Editors -> Text Editor -> Annotations
Toggle mark occurrences (Alt + Shift + O)
Preferences -> General -> Editors -> Text Editor -> Annotations
Find the Preferences under Window,
Preferences
Window
In General > Editors > Text Editors > Annotations(1)
General > Editors > Text Editors > Annotations
(5) is to select the color and press apply.