TMG 2010 OWA Public/Private Computer browser setting

Hi,

We have a TMG 2010 array that is used for Outlook Web Access and ActiveSync.

We changed the OWA web form (picture, warning, etc).

But now the "this is a private computer" setting is not saved anymore (in the browser).

So the login credentials are not saved anymore and users complain about it.

Where can this be configured/set? Is this a cookie setting in TMG?

And do you have to reboot the servers or is a restart of the firewall services enough?

Thanks!