Hi Rob,
Sorry to hear about your experience with the Captions Editor in Storyline 360. Here's a quick recording so you can see the behavior that I get when I try to make edits to captions in a sample project file:
Based on my testing, I didn't observe any snapping to any position, and I was also able to resize the caption boxes pretty easily.
As a troubleshooting step, try doing a repair of your Storyline 360 installation if the behavior of your editor is different from mine. If the issue persists, open a case with our support team here so we can take a closer look at what's happening.
