With sync, there is no master. Any change on one member of the sync is sent to all others.

Also, some things, like settings and add-ons are not compatible between different browser versions and/or computer systems.

Are you trying to set the same home page on all your devices? Is there a problem?

There is a problem. I do want my homepages to be the same using Firefox on at least Windows, macOS and Linux. Currently, Firefox in iOS only supports one home page, so I'll wait until I can have every one of my fourteen homepages across every device I use Firefox on. Since I posted this question, I added one more homepage all about New Jersey and eight homepages about traveling to, photographing, exploring and writing about eight other states within driving distance of New Jersey. The problem I'm having is that sometimes Firefox Sync switches my home page or home pages back to what they were before I changed the home page(s) setting the last time without any warning. Here today, December 16, 2018, I'm very happy with the fourteen homepages I have now and I'd love to see how Firefox 71.0 Stable renders them all once that comes out on December 10, 2019, which is the latest future release of Firefox we have a confirmed date on right now. Then, in 2020, I'll get a newer 15.6" Dell Inspiron 2-in-1 on dell.com and see how much better that newer laptop handles the pages in comparison to my 15.6" Dell Inspiron 7558 2-in-1. I wonder if there are any reports of homepages changing to the old setting on Mozilla's Bugzilla.

Just in case the homepages switch back to what they were before the last time I changed that setting in Firefox's Options page, here they are. I want them to be in their correct order from now until at least December 10, 2019 when I upgrade to Firefox 71.0 Stable on that day. I certainly have my reasons for having these fifteen homepages in this particular order across all my Windows, macOS and Linux devices, all of which I'll use Firefox Stable on every day.

https://www.nj.gov/|https://www.nj.com/|https://www.visitnj.org/|https://njmonthly.com/|https://bestofnj.com/|https://oceancityvacation.com/|https://visitpa.com/|https://wvtourism.com/|https://www.iloveny.com/|https://www.ctvisit.com/|https://www.visitrhodeisland.com/|https://www.massvacation.com/|https://washington.org/|https://www.visitmaryland.org/|https://www.visitdelaware.com/

Sync can share data between profiles and systems. You get to choose what data is shared, but it's an all or nothing choice.

The problem is that you are sharing your Preferences. That is what is causing your issue. Turn off Preferences on the sync options page and that will fix the problem.

Note: Some things can be shared using sync without issue. Such as login and bookmark data. Other information, such as settings, add-ons, and so on might not be compatible.

This just in: At 6:46 PM EST this evening, my home page reverted again to https://www.washingtonian.com/ without notice. This is what I had it last week. I don't want to turn off sync my preferences because I want them to be consistent across all my devices. I don't remember ever visiting https://www.washingtonian.com/ on the only other device I use Firefox on, which is my iPhone 6s Plus.

As a test, turn off Preferences on the sync options page. Is the problem still there?

Type about:support in the address bar and press Enter. Under the main banner, press the button; Copy Text To Clipboard.. Now in the Reply Box on the forum page, do a right-click in the box and select Paste.

This will show us your system details. No Personal Information Is Collected.

The About Sync Firefox extension from Mark Hammond who works for Mozilla often says there was a failure with Firefox Sync each time Firefox is done syncing with my account. Once again, I changed my homepages to the following nineteen in this order. I wouldn't be surprised if it reverts back to just washingtonian.com again. Again, I have my reasons for having each of these nineteen homepages in this particular order on all the devices I use the full desktop version of Firefox Stable on. I wish Firefox for iOS would let me have the same nineteen home pages on my black 64 GB iPhone 6s Plus also!

https://www.washingtonian.com/|https://www.capitalgazette.com/|https://www.maryland.gov/Pages/default.aspx|https://www.visitmaryland.org/|https://www.smithsonianmag.com/|https://www.airspacemag.com/|https://www.baltimoresun.com/|https://www.nationalgeographic.com/|https://www.baltimoremagazine.com/|https://www.northernvirginiamag.com/|https://www.homeanddesign.com/|http://www.morgantownmag.com/|https://www.southernliving.com/|https://www.arlingtonmagazine.com/|https://www.blueridgeoutdoors.com/|https://www.chesapeakefamily.com/|https://www.ourstate.com/|https://www.nationalreview.com/|https://www.theatlantic.com/

I can't paste the information either raw data or just the text to the clipboard because it's over 10,000 characters.

Open a text / word program and load the file. Left-click once. Now <Control> A to highlight everything, then <Control> C to copy it.

Next, have your web browser go to; https://pastebin.com/

Paste <Control> P the content of the file in the window. Note: On the bottom, fill out the boxes as best you can.

Now press Create A New Paste. The page will reload. Copy the new web address, and post it here.

You can exclude the home page from Sync by setting this pref to false on the about:config page.

• services.sync.prefs.sync.browser.startup.homepage = false

Preferences that have a corresponding services.sync.prefs.sync.<pref> that is set to true are Synced to other connected devices.

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

I don't want to exclude anything from Firefox Sync, I just want my home pages to stop reverting back to washingtonian.com without warning.

Should I use the About Sync Firefox extension, copy and paste the sync data into a Google Document and share you the link here? It really is a shame I can't just copy and paste it here or attach it since it's just plain text with nothing malicious! I have my eighteen home pages in the order I want them here as a backup, so if it goes back to just one home page I had it before, I'll let you know and urge a good amount of reliability improvements to Firefox Sync across every device I use Firefox on, which will only increase over time.