Hi Elaine,
Thanks for reaching out!
We currently do not provide support for editing of published Articulate content. I'll let other members of the community chime in so they can share their experiences with editing published courses to make them more accessible.
With that being said, would you be willing to provide us with more information regarding the accessibility changes that you're trying to make to your courses? There might be a way to make those changes to your courses before publishing them. Here's a helpful article on making accessible Storyline 360 courses for your reference:
