You can NEVER set where the popup ads will apears: There is a script in the web pages that decide where the ad will go.
You can suppress them.
In your browser, you can set it to refuse un-requested popups.
You can suppress ads altogether using Adblock. An extention for Firefox that's also available for Chrome and IE, and probably also for Opera.
It a very great adon or complemantary module that very effectively remove most ads. That makes the web paged load much faster and make them less cluttered.
Electro, October 2011