Rise closed captions

Dear all

I have exported an SRT file from Premier Pro and converted to VTT file, uploaded and my captions are showing as white on white when normally they show up as white on a back shade. I now done this in PP and resaved but same thing, I don't understand why. How do I reformat captions within Rise. I have asked co pilot, Google etc and no idea.

My understanding is that you can't format captions within Rise, or can you?

Anyone have any ideas?