Why can't I change my subtitles' appearance in DVD Studio Pro?

Hello there.

So, I'm pretty confused. I created an .stl closed caption file in MovieCaptioner which I then imported into DVD Studio Pro. Understandibly (if not, annoyingly), I lost my original subtitle formatting, including font size, color, font, and the black bar I had originally positioned the text over to make it easier to read.

I'm not trying to change the captions within DVD Studio Pro but whenever I select all (or even just select one individual caption) the option to change the coordinates, etc, is greyed out and I can't select anything. And when I hit command + T and change the font, it doesn't do anything to the overall stream. I just want to make the subtitles larger and add a black bar behind them. Not sure what I'm doing wrong..

Thanks in advance!