To nitpick; to find fault with trivial matters or complain about insignificant details (idiomatic).
細かいことで重箱の隅をほじくるのはやめたほうがいい。
You'd better stop nitpicking over trivial things.
会議で重箱の隅をほじくるような指摘ばかりしていると、信頼を失う。
If you only make nitpicking remarks in meetings you'll lose trust.
彼女はいつも重箱の隅をほじくって文句ばかり言う。
She always nitpicks and complains about everything.