Hi, welcome to the forums,
You've discovered something that many of us have, unfortunately. As far as I'm aware, the function of the button library has not changed (although I haven't tested it in 7). A few workarounds that I've seen suggested to avoid building up a library full of unused, old buttons:
- Do all your "testing" of buttons in a new project, and then copy over the final version of the button to your actual project
- Clear your preferences (I think this works, although I haven't tested it myself. You'll lose any other preferences you've set.)
If you'd like to log a feature request for the ability to update a button (or even just be able to delete old ones), I think the link for that is here: https://www.adobe.com/cfusion/mmform/index.cfm?name=wishform&product=5