Now that Google has merged all your personal data, time to double check that you’ve removed stuff you do not want Google to use. As well as the steps mentioned in my previous posting (Google personalisation: web history isn’t the only problem http://www.rba.co.uk/wordpress/2012/02/22/google-personalisation-web-history-isnt-the-only-problem/) you might want to clear out your YouTube history as well.
Sign in to your account and go to http://www.youtube.com/my_history and http://www.youtube.com/my_search_history. The first is your viewing history and the second your search history. If you don’t want Google to use this information to “enhance your search experience” in its other products clear both of the histories and pause to stop it gathering future activity.
And another reminder that if you are fed up with Google trying to personalise your ads you can opt out at http://www.google.com/ads/preferences. Note that this does not get rid of Google’s ads altogether it just stops Google using your past searching and browser behaviour to decide which ads to display. To opt out of targeted advertising from other networks you should also pay a visit to http://www.aboutads.info/choices/ and http://www.networkadvertising.org/managing/opt_out.asp.
Update
I should have said that the opt-out of targeted advertising is done via cookies on your computer and so is computer and browser specific. If you or your system periodically clears cookies then you will have to opt out again. You do not have to be signed in to a Google account to do this. There is also a Keep My Opt-Outs plugin for Chrome.
Further update
I’ve just checked a very old Google account of mine that was used for news alerts but does not have a Gmail account or anything else associated with it (it was set up pre-Gmail). I can log in to YouTube with it but when I try to access the My History page to delete search and view history it insists that I set up a channel, which I do not want or need, before I can do it. Tell you what, Google, I’ll just delete the whole account.