The default sorting is by which topic has the newest reply, I want to see the newest topics posted. Where's the sort button?

At each board, you will see columns with headers like

Code:

Subject Started by Replies Views Last post

At the column with Last post, you can click on the arrow Up or Down and you will get two following links in the web browser url.
https://bitcointalk.org/index.php?board=24.0;sort=last_post
https://bitcointalk.org/index.php?board=24.0;sort=last_post;desc

The first link filters oldest replies in the board.
The second link filters newest replies in the board.

You can use the Arrow, change it to Up or Down, or use the direct link with

Code:

;sort=last_post
;sort=last_post;desc

at the end of an URL link.

Thanks, that worked.