That is simple: Whether you are logged into Google or not, they have 3rd party trackers in the majority of pages you visit. And they have a variety of other ways they could use on you to collect even more. Using an Android phone, for example.
BTW, you might want to use something different than Yahoo there too (but keep the Yahoo account around, maybe as a throwaway email for temp subscription and such): https://news.ycombinator.com/item?id=17859138
@aschrijver thanks, this helps me make a decision. Not being in the tech business, it’s hard to make informed decisions without this type of information. Its no wonder all our online information is being used- most people don’t understand what is really happening. Most people I work with in healthcare have no idea what I’m talking about hen I peak about privacy concerns… Even with my limited exposure, I wondered if it was my phone- I guess that is why some of these new phone companies are emerging like Sempio.
Understandable. Did you install a ad-blocker, or tracking blocker in your browser? I use Privacy Badger, an extension to Firefox (or Chrome, but I prefer FF since it is open-source and way more privacy-respecting).
With privacy badger you can see on each page which trackers are there and make the settings as restrictive as possible (disable a tracker, and refresh the page. If it looks good, keep it disabled). So I hardly see ads, nor do I have ads following me on other sites.