Please do not reply to a 7 year old topic. Create a new topic if and reference the old topic if you feel it is relevant. Unless PayPal moved things around again the settings are found below as per the description above those parameters.
My account - Profile - My selling tools - API access - Request API credentials - Set up Payflow Pro API access
If you don't see a API Access option under my selling tools in your PayPal account then contact PayPal to be sure your account is allowed to access those features. They may have moved them to a different location otherwise you can try using PayPal Manager below to access those settings.
manager.paypal.com/
Note PayPal Advanced is basically in maintenance mode. They've replaced this implementation with their Payflow API which is supported in the PayPal Pro gateway. If you want hosted checkout I suggest not using either and just using the core PayPal gateway.