Losing rollover comments when images are small? Answered

I've got images in my instructable with rollover comments.
Two questions:

1.  what exactly are those called?

2.  when the image is shrunk on the instructible, it doesn't show the rollovers for the image.  Is there a way to make them show up?

In this screenshot of https://www.instructables.com/id/Cheap-Sturdy-1-Hour-Quadcopter
All three images have comments, but the overlays don't show up in the smaller images.

Many TIA!