Why would Captain Beatty suspect that guy has books in his house in Fahrenheit 451?Also according to Captain Beatty how did technology change people?
I assume you are talking about Montag when you say "that guy." Beatty might have suspected Montag had books because Montag had started acting like he had doubts about his work (after the old lady died). But they didn't burn Montag's house because of suspicion. They burned Montag's house because his wife turned him in -- she told them he had books there.
Beatty says technology changed people by making them think less. It allowed them to have shorter attention spans and to just want (and get) "cheap thrills." So technology led to less thinking and more happiness, according to Beatty.