bbPress

Add the edit-post-attributes.php file to bbPress' my-plugins/ directory and activate.

A new set of options will appear below posts when you are editing them.

There is currently no validation on the changes you make, if you set the date out of bounds you may cause the topic to disappear.

The plugin will properly correct the last poster for the topic (or first poster) as necessary if you change a post author.

enter User Login, not their Display Name when changing authors, it won't work if the plugin can't find a match for the username.