ihr vs du
Having trouble figuring out which one to use in sentences
If you are talking to one person (who you know well, maybe a friend) you would use "du". If you are talking to several people you would use "ihr".
Du liest ein Buch. (You are reading a book.)
Ihr lest ein Buch. (You are reading a book)
Take a look at the ending of the verb which changes according to the pronoun who does something.