So you've setup Pixel for Mac or a Raspberry Pi and your keys don't match what you are typing. Well, maybe you need to change your keyboard layout.
Got to Menu > Preferences > Mouse and Keyboard Settings
Choose the Keyboard Tab and click on Keyboard Layout
Here you'll find the Default setting is English (UK)
Just change the settings to match your Keyboard Layout. In my case, it's United States > English Macintosh.