As instruções para bloquear ou desbloquear a pesquisa segura são aqui
Lock or unlock SafeSearch
Visit the Search Settings page. To turn on
SafeSearch, check the box next to "Filter explicit results." To lock
SafeSearch, click the Lock SafeSearch link next to "Filter explicit
results." At this point, you may be prompted to sign in. Once you're
signed in, confirm that you want lock SafeSearch by clicking Lock
SafeSearch. You'll see a confirmation page once the lock is on. To
unlock SafeSearch, follow the same instructions and click Unlock
SafeSearch instead of Lock SafeSearch.
Lock SafeSearch on multiple browsers & devices
If you have more than
one browser on your computer or tablet, you need to set the lock on
each browser on your computer or tablet. If your computer or tablet
has more than one user profile, you need to set the lock on each
profile. The SafeSearch lock only works if your browser allows
cookies.
Tips for locking SafeSearch for network administrators
If you
deploy a proxy on your web traffic, it may be possible to configure
your proxy to append &safe=strict to all search requests sent to
Google. This parameter enables strict SafeSearch for all searches,
regardless of the setting on the Google Preferences page.
This technique will not work on searches done using SSL Search. Learn
more about SSL Search
Por padrão, acredito que a pesquisa segura está desativada. Se estiver bloqueado no seu navegador, você verá isso:
Se você fizer isso, alguém já fez login e bloqueou, ou você tem um proxy para aplicá-lo. Tente usar outro navegador e veja se ele está bloqueado e verifique suas configurações de proxy para ver se está definido. Se assim for, pode adicionar &safe=strict
às suas pesquisas.