Changing password of your PayPal account doesn't mean that Microsoft can stop charging you. This might be a pre-approved payment to Microsoft. In order to stop this, you need to cancel the billing agreement your PayPal account have towards Microsoft. You can do this in 2 ways.
First, you might want to remove your PayPal account from the payment methods in your Microsoft account.
Second is to cancel your billing agreement with Microsoft. To do this, go to your PayPal settings -- > Payments --> Pre-approved Payments --> Microsoft --> Cancel.
