An Administrator has rights to configure and customise the system. They will have access to the "Settings" icon at the top right corner (refer to the screenshot below). A user who is not an Administrator will not be able to see this icon. To make a user an Administrator, go to How do I make a User an Administrator?
Being an Administrator does not give a user the right to access an Issue. Users can only access the issue when granted the Issue Viewer, Issue Handler, or Issue Manager role.