A few details to keep in mind once you sign up:

1 - When you are shopping on a computer browser - you must go to smile.amazon.com (not amazon.com) in order to receive donation credit from your purchase.

2 - When you are shopping on an iOS or android phone app - you must go in and "allow" Amazon Smile for phone purchases in the app.  (You need to have already registered on your computer before being able to allow in app.) In the app, click on the main menu icon at the bottom of your screen, click on "Gifting and Charity", scroll down and click on Amazon Smile. Click the drop down menu next to "mobile app" and select "on".