Is it possible to extend "new posts" count?

[TakeFive]

I'm new here, but I've been on the Guns Network for awhile and it uses the same software as Calguns. I like to use the new posts feature to get all the new info across all forums, but the site is so active the 500 limit often only contains a day or two of posts. Is it possible to user select the limit for new posts? Am I just missing something? Thanks in advance for any help.