• Remove trash from the top toolbar

• Preferences → General

• Network Settings → Settings → [✓] Enable DNS over HTTPS → OK
• Preferences → Home
• [×] (Top Sites, Highlights, Snippets)
• Preferences → Search
• Default Search Engine → DuckDuckGo
• Search Suggestions → [×] Provide search suggestions
• Search Shortcuts
• Remove (Yandex, Amazon, Bing, Google, Wikipedia)
• [x] (Tabs, History)
• Preferences → Privacy & Security
• Enhanced Tracking Protection → Custom
• Cookies → All third-party cookies
• Tracking content → In all windows
• Send websites a “Do Not Track” signal → Always
• Cookies and Site Data → [✓] Delete cookies and site data when Firefox is closed
• Logins and Passwords → [×] all
• History → Use custom settings for history
• [×] all
• [✓] Clear history when Firefox closes → Settings → [✓] all → OK
• Address Bar → [×] (Browsing history, Open tabs, Top sites, Search engines)
• Firefox Data Collection and Use → [×] all
• Security → Deceptive Content → [×] all
• HTTPS-Only Mode → [✓] Enable HTTPS-Only Mode in all windows
• about:config
• identity.fxaccounts.enabled = false
• beacon.enabled = false
• dom.battery.enabled = false
• dom.event.clipboardevents.enabled = false
• geo.enabled = false
• media.eme.enabled = false
• media.navigator.enabled = false
• media.peerconnection.enabled = false
• network.dns.disablePrefetch = true
• network.http.sendRefererHeader = 0
• network.prefetch-next = false
• privacy.firstparty.isolate = true
• privacy.resistFingerprinting = true
• privacy.trackingprotection.enabled = true
• webgl.disabled = true

• reopen Firefox
• Firefox Addons
• Privacy Badger
• uBlock Origin
• AdGuard
• HTTPS Everywhere → [✓] Encrypt All Sites Eligible is ON
• I don't care about cookies
• Firefox Multi-Account Containers
• delete all containers
• create Facebook Container → open fb → click Always open this site in FB container
• repeat with WhatsApp, messenger, Instagram
• the same for yandex, google, vk, telegram, etc.
• Arc Dark Theme