Close caption crashing

I am working on a Mac running macOS Big Sur.  I am trying to edit a recording and add close captions. Whenever I try to remove one of the captions by using the  minus sign my captivate program crashes. Does this happen to anyone else? While I am would be to happy to find a workaround to be able to remove captions I still would like to know why this is crashing.

Video files for captivate

Do I have to convert my video files to MP4 format myself or does Captivate do it automatically?

Soundflower

Is anyone using Captivate on a Mac and has experience using Soundflower to capture audio. If yes, what were the pro and cons?

Themes

As a new user of Captivate I find it difficult to understand why when I chose a theme for a project that I don’t like and I want to go back to the previous theme, I can’t just undo. maybe there is a good reason for this that I will discover later on as I become more experienced. However for now, I am not enjoying this tiny bit of the user experience.