It's hard to troubleshoot without seeing the .story file, but I'll give it a try.
Best guess: check the Slide Properties, and be sure they are set to "Resume saved state" when revisiting (not to "Reset to initial state").
If it's a trigger issue, you may have to use conditions to ensure that any trigger that disables a button only runs when appropriate.
If none of that helps, I suggest you upload a copy of the .story file that has only the slides involved in the issue. That will make it easier for someone to investigate the issue.
