Setup root macox SDK for qt

here my qt-error :

:-1: Warnung: no such sysroot directory: '/Applications/http://ift.tt/2cMawHw' [-Wmissing-sysroot]

---

On my System exist just : '/Applications/http://ift.tt/2xECnpe'

But I can't fix it with : enter code here

macx {
    QMAKE_MAC_SDK = macosx10.13
}

Do you have an idea how can this link error?

Thx ;)