unfortunately 56.0.2 is no longer safe to use for every day use do to secuity issues, but 52.5.0 ESR is. It will continue to get security updates until May 2018, and you can download and install it from this page: https://www.mozilla.org/en-US/firefox/organizations/all/ <b>Note : Legacy Extensions will be deleted or removed in any version update after May 2018</b>. You should make a backup of your Profile before going back and just because: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles https://mozilla.github.io/extension-finder/ and https://www.howtogeek.com/333110/how-to-customize-firefox-quantum-and-remove-the-white-space-around-the-title-bar/ Please let us know if this solved your issue or if need further assistance.

Alternatively, as ESR is not really meant for home usage, what do you not like about 57? It is twice as fast and far more stable than 56 and before, so you should update.