Not sure about the Z-Wave switch, but I think you're pressing the button for too long, you just just tap it once to start the pairing process.
For the PIR sensor I'm certain you're pressing the button for too long, it needs a quick tap, that's it, as in less than 1 second, so in other words, you're never starting the pairing process.
To reset the ZigBee sensors from us, you need to press and hold the button for 10 seconds.