How do i use my MacBook Pro on iPhone hotspot? I have crappy Wi-Fi and want to use my iPhone as a Wi-Fi hotspot for my MacBook, but the iPhone seems to be connecting to the crappy Wi-Fi rather than cellular.

How do I force it to use cellular?
Simply turn off the Wi-Fi on your iPhone, and share your cellular connection through USB cable from your iPhone to your Mac.

If you don't otherwise need the crappy Wi-Fi network you have, just turn it off, most probably on your Internet connection router.

To improve the quality of your wireless environment, and if you don't use it to access your iPhone, I advise you to turn off Bluetooth on your iPhone too.