I have an old PHP class for paypal, but the credentials in the file don't match what I get from the paypal console.
its a very old file and I haven't had need to change it for a few years, so maybe things are different now.
(I didn't know which tags to apply)
the file looks like this:
* API Credentials
* Use the correct credentials for the environment in use (Live / Sandbox)
* @Var array
protected $_credentials = array(
'USER' => 'username.my_domain.co.il',
'PWD' => 'PASSWORD',
'SIGNATURE' => 'ABCD1234ABCD1234ABCD1234ABCD1234ABCD1234',