I think what you are talking about is the "Widow/Orphan" control, which makes sure that there are no single paragraph lines at the top or bottom of a page.  It can be found in the "Line and Page Breaks" tab of the "Line Spacing Options" Window.

The only thing about it that bothers me is that it creates uneven bottom margins at the end of a page. I'm sure there's a very easy fix for this, but I haven't discovered it.

As for your settings randomly changing, I have no idea. Virus, maybe?

Scribophile looks interesting, but I would actually suggest Book Country.  It's a critique/discussion community for genre writers, set up by Penguin, but completely separate from them.  The process there is that to post your work, you review/critique 3 pieces, and then your work will be public.  You can post as much or as little as you want, and different people can view different amounts--nonmembers can see about 3000 words, members can see about 10,000, I think, and I believe contacts can see all of it.  Plus, when they were setting up the site, they spoke with agents, editors, etc, to make sure posting wouldn't change first publishing rights or chances of getting picked up, or anything. 

They will not allow anyone under 18, though, but on twitter, they've linked to http://writeonteens.com/ for anyone under.

Oh, one of the main people behind it is Colleen Lindsay, who used to be an agent and has worked for several of the publishers.

The big thing I consider a good reason for going there--two authors have been picked up--Kerry Schafer and Michael R Underwood--both with at least 2 books contracted. Underwood's book, Geekomancy, came out from Pocket Star this past Tuesday so it could be hyped at SDCC.

Which reminds me, I should review some stuff so I can start putting up my draft.

It would be a rare occurrence to be sure, and very situational.  I can think of examples in certain contexts, but for most of them I can think of some other ways to inform the reader after the fact if necessary.  Like if you have an MC that really needs to go unconscious, and thus events must happen in the interim; but in that case it would make sense for another character to catch him up after the fact.  The only really binding situation I can think of is when you are specifically wanting the Reader to see things coming before the MC does.  But clever foreshadowing should be able to pull that off, without the need for a perspective shift.

I personally dislike this technique.  I'm perfectly fine with multiple perspectives, but if it's done as a one off, or just to provide a bit of dramatic tension (where the audience knows something but the protagonist doesn't), it always lessens my immersion, and frankly strikes me as lazy writing.  It's perfectly possible that someone has used this technique to great effect, or that I'm unjustly discounting it because I'm stubbornly set in my own preferences.  I'm not any kind of literary buff, and have no formal training.  I'm just a guy who reads 5-6 novels a month, and would like to write stories for a living someday.  Still, the stories I find most engaging tend to either stick with one perspective to maximize empathy, or weave together a braid (or in some cases, a tapestry) of perspectives together to allow for more complexity and broader scope.

The only reason that I can think of to do this is to build tension. If you know something is happening that the main character doesn't, it can heighten the tension as you wait to see how he/she is going to deal with it when it surprises them. Maybe there are other reasons but I can't think what they would be.