Use external WiFi adapter instead of internal I've been trying to get an external USB WiFi adapter to work with OS X 10.10 (Yosemite), instead of the internal one that came with my iMac, but I can't find anything in system preferences whatsoever that lets me configure it, I looked in network settings but couldn't find any option to select the adapter I want to use, it just lets me pick 'WiFi' which is always the internal one.

The adapter I'm trying to configure is an Alfa AWUS036NH, any help will be greatly appreciated!
You need a proper driver to run your external Wi-Fi adapter.

Check this page, choose Product Category -> Indoor Wireless, Product Model -> AWUS036NH, Type of file -> driver and solve a captcha to get to the download page.

Download the driver for Mac OS X 10.9 and try to install it. If this driver doesn't work with Yosemite you probably have to contact the support there.