Content creation

I'm offering certification courses where it is really important to have the students watching the videos and I would like to build in features that help ensure this.

My Learndash courses mostly use Vimeo videos. I would like to accomplish the following. 

I am creating Image hotspot with quite a lot of content. My question is how can I replace the main background image? I see editing option, but I can't find a button to re-upload the main image.

Thank you for your help!

I've created a few Multiple Choice questions, which I now realize are all stand alone questions.  Is it possible to combine them into a single assessment, perhaps with the  Quiz (Question Set) tool type?

Brent