To Turn Off Gmail’s Conversation (Threaded) View:
- Go to the main Settings page
- Look for the “Conversation View” section
- Select the option "Conversation view off" to turn it off
- Save your changes.
|Image from http://3.bp.blogspot.com/_ysAuSNZolhE/TKNic5tvYqI/AAAAAAAAAUU/QTFmqh7UdwQ/threaded.png|
For more details, see the following official posts from Google: