What's With Google Search?

[SEO]

I didn't see any posts related to this, so I'm starting a new thread. If this is a repeat, please send me to the thread to read the responses. What's with Google Search? When I'm logged into my Google account my sites are higher in the searches for specific search terms. When I log out of my Google account and search using the same terms my sites are lower on the page. What's with this? It happens to me and my husband whenever we are logged in to our Google account our site is higher on the page. As soon as we log out we fall to the bottom! I don't get it. Is there a "true" gage or is this just the way it is. Has anyone here had the same experience?