No you can't use it interchangeably. This pretty complicated to use. It relates to different level of knowledge. "Savoir" is a bit stronger than "connaitre". Sometimes the sentence structure needs to be different. - Je connais son âge - Je sais quel âge il a. But it also depend on the sentence. You can use "connaitre" for knowledge and "savoir" for the skills. for example : - Je connais l'histoire de la France. - Je sais parler français. This the kind of thing you need to practice a lot with natives to be confortable with.

Thanks, yeah. I did see it ^^ just right now.

Have a look in the list, someone asked the very same question a few days ago.