Tip is for OS 10.11 – El Capitan
You need your Apple ID more and more these days. That means you also need your Apple ID password. But people have been known to forget those passwords. (Hint: Keep them stored in Keychain) And for that matter, people sometimes forget their Apple ID. You can fix both these problems.
If you have forgotten your password, enter your Apple ID in the box (red arrow). If you have forgotten your Apple ID, click on the link that says Forgot Apple ID? (green arrow).
For forgotten passwords, once you enter your ID and click, the next window gives you two options. The first is get an email with instructions sent to your email address that ends in me.com.
The second is to answer security questions. Choose your option and click continue. Follow the directions for either option.
For forgotten Apple ID, the next window will ask for your name and email address. Be sure to use the email address associated with your Apple ID account. Continue to follow the directions.