"Sync encountered an error while syncing: incorrect user name and password" I go into the tools pulldown menu, select "reconnect to sync" and enter my password and everything is fine again for a day or so.

I set up Firefox Sync and it works fine. Then a day later or so, I get a banner on the bottom of the browser window that says "Sync encountered an error while syncing: incorrect user name and password" I go into the tools pulldown menu, select "reconnect to sync" and enter my password and everything is fine again for a day or so. When I get the error banner, I have noticed that the Firefox sync cookie is gone "accounts.firefox.com" which explains why I am getting this error. I do have "accept third party cookies" set to never, but I have accounts.firefox.com listed as an exception. I have the exception entered as "allow" accounts.firefox.com (as advised here https://support.mozilla.org/en-US/questions/1004582) I also have "clear history when Firefox closes", and specifically made sure "Saved Passwords" was unchecked Yet when this banner error message occurs I noticed that something altered my settings where "Saved Passwords" is now checked. Wondering how this can happen. Could a 3rd party add-ons modify my privacy and cookie settings?