You also need to uncheck - use a background service to install updates. I have mine set to check for updates, but let me choose so get bugged a few times a day to install the update, then decline each time. So far not been upgraded to 57. I too have add-ons I cannot live without.

There are 2 possible replacements for you that work on 57, read the reviews for each before trying them.

https://addons.mozilla.org/en-US/firefox/addon/rikaichamp/

https://addons.mozilla.org/en-US/firefox/addon/rikaichanext/

Hope that helps.

Try this: There is a very simple an effective way. Firstly there is no “click a button option” to stop Firefox updating. It will ignore all settings and continue to update! This is how you stop it: Open file explorer. Navigate to c\:program files(x86)\Mozilla Firefox\ Now find the files named “updater” and delete them all. Also to be doubly sure, delete maintenanceservices.exe Updates will never run again. The second part of deleting the services-I left that and it didn't try to update if it does then you might want to delete it then. Before that close and run FF again and then check your settings and make sure the "Never" check for update is checked and it doesn't try to update.

Thank you guys very much looks like I'm good to go. Super appreciated.