I agree with the other response, keep an eye out in front and keep them close to you - with Rocky I am still using a lot of a treats when he comes back to me but he always comes back when I call even when running up to people and dogs. I also use the sit command until other people pass, I get him to come to me well before he gets to the other people/dogs and make him sit with a treat right in front of him and keep his attention with that til the other people pass.

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Proud owner of Rocky the Yorkie, born July 2008, who came to live with us at 8 weeks old
and
Ellie the Yorkie, born February 2012, who came to live with us at almost 8 weeks