I cannot see all stores on QuickFile screen like before. I have selected it in the settings screen.

This is because in Version 6, All Stores exclude other exchange folders apart from default.  This is done to improve speed.  However, the following are instructions, if you need to search folders from other stores.
  1. From Microsoft Outlook, go to your Inbox 
  2. Go to Standss Outlook Addins tab
  3. Click More from QuickFile Group
  4. Click on Settings to open QuickFile Settings Screen
  5. Go to Data Files tab
  6. If All Stores is not selected, select it
  7. Tick "Index Other Exchange Folders too"
  8. Click the Yes button
  9. Click OK button to save the settings
  10. Choose to re-index