In Final Cut Pro 10.2.3, I can change all of the text at once. You open the Inspector, select the Text tab in the Inspector, use the scroll down bar and click on “Advanced.” Then scroll more until you see the Text options. Advanced will get you the option to change 3D text, color (face), opacity, glow, drop shadow and others. Once you see the options you want, look at your timeline in your “Project.” Hold down the shift key and use your mouse to select every text bubble in the timeline. Once all text bubbles are selected, go back to your Inspector and use it to select the features you want to change. Done.