The Session Resurrection
By default, macOS includes a system-wide feature called “Resume,” designed to restore your exact working state after a reboot or after closing an application. In Safari, this means that if you completely quit the browser (Cmd+Q) while you still have twenty tabs open, those exact twenty tabs will automatically reload the next time you launch Safari. While this is helpful if your Mac crashes, it is a massive privacy risk and a performance drain if you purposefully quit the browser to clear your workspace, only to have all your previous research (or private browsing sessions) instantly reappear on screen when you open it again.
Configuring Safari’s Startup Behavior
To ensure a clean slate every time you browse and stop macOS from automatically restoring your previous Safari tabs, you must alter the browser’s specific startup preferences.
Open the Safari browser. In the top menu bar (next to the Apple logo), click on Safari and select Settings (or Preferences in older OS versions). Ensure you are looking at the General tab, which is the first icon on the left. The very first option is a dropdown menu labeled Safari opens with. By default, this is often set to “All windows from last session.” Click this dropdown menu and change it to A new window. Next, look immediately below it at the New windows open with dropdown menu, and ensure it is set to either Start Page or Empty Page. Once these two settings are adjusted, you can safely quit Safari. The next time you launch the app, it will open to a single, blank tab, completely ignoring your previous session history.