If you’ve previously installed WordPress, you should upgrade it from within your WordPress Dashboard.
With this version, we’ve also made a change to the default settings used by our one-click WordPress installer for new sites. A newly-installed site now has comments and trackbacks initially disabled.
This does not affect previously installed sites at all, and customers installing new sites can easily change the settings to allow comments and/or trackbacks.
We did this because we were seeing more and more sites where a customer installed WordPress, created a few pages using the default options, didn’t look at it for a few months, then found 150,000 spam comments promoting fake Louis Vuitton handbags and porn sites. We think that “let strangers add stuff to my site” should be a feature that you knowingly choose, not the default.