We don't all use a QWERTY keyboard. There's also AZERTY which is used by most French speakers. There's also the German QWERTZ layout. But most people use QWERTY.
Does the arrangement of letters on a keyboard baffle you? Well, it's been that way since Christopher Sholes invented the typewriter in 1868. Though there seems to be no logical reason why our keyboards bear such a weird matrix of letters, QWERTY keyboards have quite a rich history, and the layout is something we've grown accustomed to.