can't hear FaceTime on Macbook Pro Retina Mid-2015 I can't hear people when they FaceTime me, of course at first I thought they had muted themselves but actually the call works perfectly on my iPhone 7.

I guess this is a problem with the FaceTime app on my laptop, but I don't find any sound settings in its preferences.
The audio options are available in Facetime in a perhaps confusing place:

Open Facetime. Then in the top menu choose "Video" and at the end of this menu, there's a subtitle "Output" where you can choose the audio device. Choose the speakers you want here, and you should be able to hear people on calls.

If you still cannot hear the other party, then open System Preferences > Sound > Output, and select the device you've selected in Facetime also. Now you should see an "Output volume" slider, where you can adjust the volume.