I'm using the LyX 2.1.0 beta 2. The "What's new in LyX 2.1" page at http://wiki.lyx.org/LyX/NewInLyX21 says "Users can now turn off the "justified text...." and it is indicated as being documented but I can't find anything about in the documentation nor can I find anything in the Preferences. I'm using OS X.
Jerry