Johathan,
You are probably trying to change the colors of one of the light streaks, I would guess. It’s a little complicated, because their colors are keyframed. You need to go to the Shape tab of the Inspector, then to the Stroke pane – at the top is the Color Over Stroke parameter. Click the Animation menu (the diamond that will be solid or hollow, depending whether or not your playhead is parked on a keyframe), and choose Show In Keyframe Editor.
Now move the playhead to each keyframe and change all the colors at that point in time, then repeat at each keyframe. Note that it isn’t strictly necessary to do this in the Keyframe Editor – you could just use the Animation menu to navigate to each keyframe or press Shift-K – but it does make it easier to see exactly what is going on.
—
Mark Spencer
Freelance Producer/Editor/Motion Graphics Artist
Apple-certified Master Trainer
Author, Motion 4 from Peachpit Press
https://www.applemotion.net