How to see all changes made by an admin
Administration Notifications this is a simple module that can be used for communication of site changes/updates between the site designer/developer, and the site owners. 


  if you maintain a drupal installation for another company, you can use
  this module to inform them when you have updated versions of the site
  (ex drupal 7.1 -> 7.2), updated modules on the site (i.e.
  Administration Notifications 7.x-1.0 -> 7.x-1.1), added new modules,
  or changed the site design in some manner.


or you can try Activity module. 


  The Activity module keeps track of the things people do on your site
  and provides mini-feeds of these activities in blocks, in a
  specialized table, and via RSS. The module is extensible so that any
  other module can integrate with it. The messages that are produced are
  customizable via the admin interface and are context sensitive.