PayPal API Credentials - Where to find them
PayPal has changed their customer account page layout. To find or set up your api credentials log into your Paypal account.
Look in the left column for the "Selling Tools" heading. In the Selling Tools list find and click on the link for "Seller Preferences". The profile page will load.
On the left side of the page find 'API access'. In the 'API access' row look to the right and click the 'update' link.
If you need the credentials for your own website you will want to set up option 2.