There are many legitimate reasons for keeping search histories private, but up until now the only way to do this on Google search or YouTube was to employ the incognito mode. Anyone not using incognito mode can find details of all searches and history on Google and YouTube at activity.google.com. Meaning anyone who has access to a device on which your login is still active can view your search, watch, and query history. You can choose to enable verification and require anyone trying to look at your activity history (including yourself, obviously) to enter your Google account password before the history can be viewed.
To activate this protection visit activity.google.com. Login and select the “Manage My Activity verification” link. You’ll see a pop-up window with a button marked “Require extra verification”. If you select this and save it, you will then be required to input your password again as confirmation of authorization. Going forward, any attempt to view your search & browsing history will have to enter your Google password.
Simple password protection isn’t the highest available level of security; if you are trying to conceal your history from someone who shares your account or has gained access to your password for some other reason, they can easily get around simple password protection.
If you’re seeking to ensure that your history is completely invulnerable to prying eyes, you could consider either automatically or manually deleting all your activities. By visiting the My Google Activity page and selecting Web & App Activity > Auto-delete you can set Google to auto delete all history and activity logs after 3, 18, or 36 months, or, on the same page, you could set Google to never save your history; alternative, you can opt to manually delete items you don’t want to be seen.
Finally, if browsing history and security are particularly important for you, you may want to try some additional alternatives.
DuckDuckGo.com offers anonymous searches and a much greater respect for privacy than Google.
The TOR Browser offers much stronger search and browsing security options.