I didn't know you could do this (I thought there were only a few handpicked charities). If you want to make a similar change your smile charity go here:

https://smile.amazon.com/gp/charity/change.html?ie=UTF8&ref_...

Then install the "Smile Always" plugin to redirect you to smile:

https://chrome.google.com/webstore/detail/smile-always/jgpmh... (The offical amazon one doesn't auto redirect AFAICT)