I've set up a number of kanban boards and projects and on both I want to be able to add an approval to a task, e.g. assign a task to a user and not allow the task to move from in review to complete without being approved by the nominated approver. I don't seem to be able to get this working correctly as when I've set up a classic project and added an approver, it doesn't actually do anything or prevent the task moving from one stage to another.
Complete novice so please let me know if any further information is correct or if you're able to help please get the crayons at the ready...