Why can't I change Google's preferences?

I do a weekly deletion of my temp internet files, cookies, pword, etc. so One: To make sure that nobody can access previous account info and Two: To de-clutter my hard drive. So I just deleted the clutter and I had my Google settings on strict safe search to avoid... stuff. Now when you delete temp files, these preferences are lost so I change it back to strict and type in Earth on images to make sure it worked and it acted like moderate and even said moderate. I tried many more times with no luck. I did a Kaspersky and Anti-Malware scan and nothing came up. My cookies are enabled but it still won't work. What is wrong?