Add amont to Paypal button

I use a custom button for Paypal payment but i don't find how i can add amount like this https://www.paypal.com/us/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=XXX&amount=1 https://www.paypal.com/us/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=XXX&amount=2 https://www.paypal.com/us/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=XXX&amount=5 Parameter amount not work Any solution for add a custom amount in link ? Or if you have an api for add multiple payment methods ? Thank