How do I get the background to be fixed in place?

I’m trying to make a demo presentation of using the Prezi video app. I originally created a background image based on one of the sizes mentioned at the bottom of the page here.

When the different subtopics show, the background shifts and makes it so that what I want seen is no longer viewable.

Here is the video that I made [jump to 1:45 on the video]:

I’m writing a blog post about teachers using Prezi. If there is a way for my image to be fixed and not move, please let me know. I’d rather clarify to the teachers how to avoid this than mention this as being a downside.

I greatly appreciate your help.

Hi @Bruce_Ellis,
Thanks for reaching out!
You should be able to edit the zoom area of a subtopic so it is zooming where you want it to zoom exactly.
For this I would advise you to right click on the topic / subtopic and select advanced topic editing.
This should show you the zoom area of the specific topic or subtopic.
If you click on edge of the zoom area you should be able to move it around.
Hope this helps!