@Cynthia Ottenbrite - This is not currently possible - there is even a Wish List Idea that I suggest you vote for: Ability to enable / disable 'download' button.

However, while we all wait for a solution/new feature, I think I have found a fairly quick workaround:

1. Put a small text box on the board.
2. Put your image over the text box - if you can see the text, just right-click the text and select Send to back (or press the Page Down key) - or you can Copy and Paste the image onto the text (many options!)
3. Select both objects by using the Shift + drag shortcut to drag over the image and therefore selecting both the text box and image (even though you can’t see the text box).
4. Lastly, Group the objects.

Here are the steps in action:

And here’s the result - you shouldn’t get a download image button/arrow when trying to download the last image on the right (with the green checkmark above it):

https://miro.com/app/board/o9J_kl7s10c=/

However, the user can always still capture the image using screenshot software.

Thank you for your response and recommended work around Robert.  I believe we also found that if we lock all the content on the board, that an individual with VIEW rights only would not have access to the unlock or download features.  Good enough of a temporary fix until there’s a new feature developed for the site.