"I know where I am."
Translation:Sé dónde estoy.
Conocer means more that you know some one rather than some thing. It's used more in reference to people.
You shouldn't have used 'yo' twice, it is redundant in Spanish. Native speakers tend to omit personal pronouns.
Also estoy can be used for temporary things example: Estoy aquí. (I am here.)
Why is that Yo sé donde estoy is incorrect and the correct answer is Yo sé en donde estoy. Why is "en" is needed for Yo sé but not Sé?
I think what they're getting at is the use of the preposition en instead of a, which a native English speaker would want to make "at."
Dónde is used when asking "where" questions, adónde is used in questions that indicate motion toward someplace. ¿Dónde estás? - Where are you? ¿Adónde vas? - Where are you going?