Facebook Integration settings keeps crashing upon saving

Hi i've been trying to save my easysocial facebook integration settings, however, it keeps sending me to an error page (403 forbidden) each time i try to save it. i followed the steps here, (https://stackideas.com/docs/easysocial/administrators/configuration/facebook-configuration) and input my app id and secret etc accordingly.

i have logged in with my super user account into my console to do the changes and have all rights to make changes i believe.

can anyone help me with this ? I'm not sure what's wrong as i have logged in and out, and waited say 2 hours before trying again and it keeps hitting with the 403 error