I have set up the membership plugin, activated the payment,

I have set up the membership plugin, activated the payment, Paypal standard. I have set up the credentials in paypal; but when I go to the registration page, I see a signup button, not a paypal subscription button. And when I tested it I was allowed to register, & went straight into the account. was not sent to paypal to make the payment. been pulling my hair out over this. & I am certain it is something fairly simple.
???