email as username

Hi,

Probably a setting or two I've done wrong here...

I've just noticed in my dashboard that some of the members items in the feed are displaying their email address...not a usual username.....they're FB registrations.

Now, I assume that this is because FB login uses email as a 'username'..

If I look at ES admin Settings > Facebook > Registration section, I can see that the bottom option is to specify which data from facebook the site uses as the username.
I assume, that I should have set this to 'Fullname' and not, as I did, email.

If I change this to 'Fullname' will future registrations from FB have their Real Name displayed on their posts, or is their another field that they fill in called 'Username'?

And....what can I do about those that have already registered? I've changed the setting to Fullname, but their emails are still showing in their posts as their username!
If I get these users to change their username then will they have to resort to logging into the site the standard way, and not just click on the Facebook link?



Thanks
Paul