Question words such as ¿Cuándo?, ¿Cómo? and ¿Dónde? always have accents when used in a question.
However, when we use these words in a statement, rather than a question, they do not have accents.
Eg. When I go to the beach…= Cuando voy a la playa…
I don’t know where it is= No sé donde está.
