Getting someone else's google search history?

Hello, I'm receiving my friend's google search history on my iPhone. The problem started about two weeks ago, when she bought one, and because she couldn't get an apple ID right away, I gave her mine to download some apps, and logged out. When the search history first appeared on my device I realized it was hers, so I changed my apple id password (i guessed that could be the problem). That did not work, I'm still receiving the webs she visits, which I find so annoying. Also, I feel like i'm invading her privacy. I've seen other people have had this problem before, but I have not find out the reason, how can I solve this problem? Thank you! (We are both using Iphone 5s and have the latest iOS)