Is it possible to edit the width of the caption box?

I thought I'd just give this a bump.  A new thing I've found out is that regardless of what the captions I create in Camtasia look like, they'll look different depending on the browser.  Does anyone have any suggestions on how to anticipate and accommodate for that issue?  I'm thinking I'll just determine what the maximum number of characters is and use that as a guideline.  Please let me know if you have any suggestions.

thanks,
Jimmy

captions display is a function of their font size and alignment

the default seems to be ADA compliant; too large for my purposes 

for a 1920x1080 HD video, I prefer to set font size to 21 - 36; can enter a lot more text on each line [3 lines allowed]