I lost all my passwords on all my browsers

Except the passwords are synced with Google in Chrome, and it worked for years before the Windows 10 Update two updates ago.  So clearly some functionality changed ...

Let's think about that: You allege that an update from Microsoft has, for months, interfered, either intentionally or unintentionally, with Chrome's ability to sync passwords. That's quite a charge. Why haven't we heard anything about this from Google?

In addition, you don't think those passwords are sent over the internet in plaintext? No, they are encrypted. So how would Microsoft be able to discern what transmissions from Chrome are passwords?

Moreover, Chrome is also my default browser, and I have all the Windows updates, and I have no trouble syncing.

In any case, if you worry that Microsoft and Google are mixing it up, try one of the third-party password managers. Microsoft can't prevent everyone from syncing passwords.

Two problems with your suggestions:

1. I don't have any account with capacity in the cloud so nothing to sync to.
2. I installed LastPass, spent ages putting all my passwords into it, then found that every time I close down Edge it loses its connection to LastPass so I am forever entering the LastPass username and password, which is very annoying.

I don't have any account with capacity in the cloud so nothing to sync to.

Oh? You couldn't post here if you didn't have a Microsoft account. And you couldn't sync passwords in Microsoft Edge if you didn't have a Microsoft account.

I installed LastPass, spent ages putting all my passwords into it, then found that every time I close down Edge it loses its connection to LastPass so I am forever entering the LastPass username and password, which is very annoying.

That's a security measure common to all password managers. It prevents whomever else is using your web browser from gaining access to all your passwords.

It's also a good idea, because your master password is the only way you have to access your passwords. So you want to remember it. (But in any case, you can defeat that feature in LastPass' options.)

Please explain how you "sync passwords in Microsoft Edge".

I have always just used Edge as a search engine, and it remembered my passwords - I never did anything particular to synchronise anything with anything so you've got me baffled.

As regards LastPass - when I login to LastPass I tick 'remember email' but NOT 'remember password'. When I return later, having closed Edge in the interim, I have to enter both pieces of information.

Id there another way to "defeat the option in LastPass" and if so, how?

Please explain how you "sync passwords in Microsoft Edge".

1. Open Microsoft Edge and go to "Settings and more" or simply press Alt+F:

2. Go to Help and feedback > Help  and type 'sync Microsoft Edge' into the search box (without the quotes) and then click on the right-pointing arrow:

3. Select the first item in the list of results:

4. Watch the video and read the post:

Note that when you sync your passwords (and other settings) they appear in Microsoft Edge on any device where you use Microsoft Edge and sign in to your Microsoft account. That includes, for example, your own computer after an update or a clean install.

I have always just used Edge as a search engine ...

Microsoft Edge is a web browser, as are Google Chrome, Mozilla Firefox and Opera. There are very many web browsers, and many of them - including Microsoft Edge and Google Chrome - are based on the Chromium Project.

A search engine is a web page like Bing, Google, DuckDuckGo and Yandex, where you enter a search term and get back search results, which include valuable information and a lot of junk.

As regards LastPass ...

I hope you won't be offended, but I'm not going to show you how to compromise your security.