From the release notes (https://www.mozilla.org/en-US/firefox/66.0.4/releasenotes/ https://www.mozilla.org/en-US/firefox/66.0.4/releasenotes/) : > If add-ons t

From the release notes (https://www.mozilla.org/en-US/firefox/66.0.4/releasenotes/ https://www.mozilla.org/en-US/firefox/66.0.4/releasenotes/) : > If add-ons that use Containers functionality (such as Multi-Account Containers and Facebook Container) were disabled as part of this problem, any lost site data or custom configurations for those add-ons will not be recovered by this release. Users may need to set them up and login again in about:addons (Bug 1549204). > Themes may not be re-enabled. Users may need to re-enable them in about:addons (Bug 1549022). > Home page or search settings customized by an add-on may be reset to defaults. Users may need to customize them again in about:preferences or about:addons I don't know if there is a way to manually recover the settings you lost. It might be a good idea to check the related links in the release notes for more info.