Changing color of text at specific second on a timeline

Can't figure out how to do this on Fusion. Just want a part of text letter to change color at specific seconds on a timeline. Character styling seems to hardcode that style to that letter. I want it to change at specific seconds not all the time. Tried clicking diamond beside it but does not seems to matter.

Are you right-clicking on the "Right-Click here to animate character level styling under the Text tab in the Character Level Styling modifier? Then you should be able to keyframe it the way you want.