Where can I see the saved checklists in a project?

Open the popup dialog for a backlog item, task, sprint, release, or project. Then click the "More" link at the bottom of the dialog, then "Add a checklist", then "Or, add a saved checklist", and then finally "Manage saved checklists".

If you don't see the "Or, add a saved checklist" link, there are no saved checklists in that project.