Welcome to the Q&A Forum

Hi there! Thanks for reaching out! My name is Erin, and I'm on the Moz Help Team. Unfortunately there's no way to set a "Global" search engine. Search engines track rankings by search engine, not globally. This means that you'll rank differently for a keyword on google.com versus google.co.uk. You'll want to just take your best guess at which search engines you want to choose. Remember, if you choose google.com (or any search engine really), you'll see results from anywhere in the world where someone is using google.com. However, each country will default to their own search engine. For example, England will default to google.co.uk, not google.com. Maybe track google.com, and then choose your other two search engines based on your best guess on where people might be searching for you. I hope that helps, and good luck! Erin