The authorisation is granted when you link a bank account (in other words, a standing authorisation to fund payments from your bank account when there is not enough balance in the PayPal account is granted when the bank account is linked, the only way to remove the authorisation is to unlink the account).
It sounds like your PayPal account information may have been compromised, possibly by clicking on a link in a phishing email or inadvertently downloading a keylogger from somewhere - if you haven't done so already, I suggest you change all the passwords to sensitive accounts and run a deep scan on your computer. If it finds anything, change the passwords again after it's been removed.
