Disabling other States or Locking a State

I created a course where navigation to each chapter stems from a table of contents. I created a variable to mark the completion of each chapter. Upon return to the table of contents, the button going to that chapter changes to a completed state which has a checkmark. It is working, but if the mouse rolls back over the button, it changes back to the "hover" state and no longer shows the completed state. I assume that any other action on the button would change the state as well. Is there a way to disable other states (especially hover) or lock the completed state so that it doesn't change from that after the requirement has been met or some other work-around for this?

Thanks!