When I started the tumblelog, the idea was short tips and I had disabled comments and trackbacks for all posts via the default wordpress settings. Hundreds of posts later, I decided to open up comments, but it was a difficult task to turn on comments in existing posts as you had to do it manually for each article… then I found a simpler way!
Under the WordPress Options > Discussion page, you can switch the default global setting for trackbacks and comments on or off, but that only applies to posts you make from that point forward. Individual existing posts have their own settings and need to be edited manually.
Then I found this powerful wordpress plugin called Extended Comment Options that lets you quickly and easily switch comments (and trackbacks/pingbacks) on or off with a single click. And indeed I could activate comments on hundreds of posts in one click. Amazing!
Powered by a set of Simple Settings and Advanced Settings, it is a must have plugin if you want to power turn on or off comments and trackback settings on a bunch of existing posts.