recent apps button setting on htc one gone?

I got a new HTC One S / Android 4.03 / Sense 4.0! via warranty and wanted to set it up. I wanted to change the setting for recent apps button in settings > display but it's not there anymore. Why? Always had it. Can i somehow get it? The only things i've done before was unlocking via htcdev, flashing twrp, backing up, restoring backup, restarting, and started installing apps. So it's the original HTC rom and i haven't done changes to rom. Did OTA after didn't found it but still, it's not there.