Firefox Bookmarks showing up on another computer

My Windows 10 PC stopped working a few days ago & is disconnected & partially disassembled. I’m temporarily using my old Windows 7 PC which I brought up from the basement the following day. They both have Firefox on them.

I saved one bookmark on the Win7 PC yesterday and it was there when I looked later. In the evening I went to use it again & it’s not there. But my Win10 bookmarks are there!!

How could my current Bookmark list show up on a PC that hasn't been used in years? Is Firefox secretly saving my data on their server?

You have Firefox sync enabled.

I looked in Firefox settings > sync and it indicates Syncing: ON. Next to that it says Sync Now. Below that it lists Bookmarks, Open tabs, etc.

I don't recall ever syncing Firefox to anything or ever going into that setting. This is the first time I recall ever looking there. I never clicked on Sync Now.

I only have Firefox on my PC and only use one PC. The Win10 PC replaced the Win7 PC. IOW there was never anything to sync my PC to.

That said, even if the old & new PCs were synced, the Win10 PC is dead, not plugged in nor connected to the the router. When I brought up the Win7 PC how was it able to access the Win10 bookmarks?

The sync settings lists my email address with an option to sign out. I presume that means my email is synced & I can sign out of that sync. How do I un-sync the bookmarks, I don't see an option for that?

The one bookmark I did save with the Win7 PC is not showing up. Shouldn't it have been added to the bookmark list?

Thanks

https://support.mozilla.org/en-US/kb/delete-sync-data-firefox-signing-out-firefox-account

Sync was turned on in your now useless computer. Firefox keeps a record on its servers when sync is on.

Turn sync off and Firefox will not store that info.

Why complain about Firefox showing you the bookmarks you saved on the useless computer? It is likely that

the one bookmark you claim is missing is likely in a folder you haven't checked in....if it was actually properly saved.

Would like to add that you should have a Backup of your Bookmarks , Passwords and Profile (which would contain both of those) at all times.

(I have been running the same Bookmarks I started in 1995)  If you are not you should be and kept in a safe place, maybe email it yourself online mail.

- https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

- https://support.mozilla.org/en-US/kb/export-login-data-firefox

- https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

At this point I cannot tell what the settings are on the useless Win10 PC. I have parts coming & maybe I'll be able to when I get it up & running. Is sync normally turned on by default? The Sync is turned ON in the old Win7 PC.

I forgot about my HTPC which runs Win7. I looked & Settings > Sync show "Sign in to sync..." and it does not have the Win10 bookmarks. Obviously it's not synced to anything. Do both PCs or devices need to have sync turned on in order for it to work?

Yes both need Sync signed in, that is how it works.

No Sync is not turned on by Default unless have it turned on.  You would have had to turn it on. 

As to if have to turn it on both I have no idea as do not use it. 

If are logged into a Mozilla Account that maybe all that is needed.

(A USB Drive works well enough after almost 20yrs of Export / Import )

I use Mozilla Firefox and Mozilla Firefox Portable on my desktop-only computer but never use Firefox Sync.

I also use Mozilla Firefox Focus in full-screen view on my Android phone but never use Firefox Sync there either.

However, just for the record, I have a Mozilla account but never use it for anything specific on my computer and phone.

There is an article on 4 ways a Firefox account comes in handy - The Mozilla Blog, which is well worth reading.

As such, even though registering and using a Mozilla account provides several benefits, I still have NO use for them.

Good luck!

I could see where having devices synced could be helpful. I just spoke with someone who uses Apple devices & has them synced. He looked up & saved bookmarks at home & went over to someone's house to work on a furnace & all the links he had saved showed up on his phone.

I use one PC & don't have Firefox on my Android tablet or phone, so I never had a need to sync anything. Apparently I must have done something some time ago & had sync turned on in the old PC and then in the new PC.

Firefox never miss an opportunity to let you SYNC into your acount, but will only do so if you accept to turn the feature ON as others pointed out.  Maybe you don't recall having turned on the feature, but if you didn't, someone in your home did because that feature doesn't turn itself on randomly.