Connection to Facebook on my MAC

I was connected to FB on my three Apple devices. I needed to verify my password to carry out a photo send on my MAC and i got the message that the username and password were not valid! I deleted the facebook details in internet account settings on the MAC and deleted the Facebook password from 'passwords'. I checked the details of my account (including username in my general FB account settings) using my iPad so I know that everything I am typing into the MAC is correct. but I cannot reconnect to FB on my MAC. What am I doing wrong?