Changing php site's domain name, what to consider with php page for Paypal?

I’m changing my php site’s domain name, what should I consider regarding the Paypal php page?
I’d need to change the paypal php files? What in particular?
And change the return to web site file correct?
What needs to be done to accomplish this?
Any other considerations reagrding domain name change?

You could implement a 301 redirect with a .htaccess if you;re using Apache. Google will pick up the new domain over time and you can phase out your old domain. With regards to PayPal - I think you should be able to change the settings for your business so you can identify yourself as another domain. Not sure on the specifics however.