error 503

Please bear with me as not very pc literate.

On my mac, I open safari, which opens my main page, apple. I then put in my question, i.e. who played x in film and it opens up normally with a big list/pages of choices to choose from. My problem is when i then choose one, it comes up with error 503. In bar it says search.mykotlerino.com

I don't know where to find this to delete or what to change it back to google

My other pc is fine. I think my husband has clicked on something and changed some setting by error.

Any help greatly received

Caz