Wordpress Permalink problem
 

Hello,
As everyone knows wordpress can give you the permalink just like:
http://www.domain.com/2006/09/28/cus...ink-structure/,
and it is very useful for seo,
but if I want to change it to:
http://www.domain.com/2006/09/28/cus...ink_structure/ or http://www.domain.com/2006/09/28/customize permalink structure/,
what I need to do?
I know the first one is the best one for seo,but I need to fix this problem.
Please advice,Many thanks for your reply:)

Change your htaccess to 777