-Forum Post per Page in not updated in database-

Hi. I want 5 post per page. when i change it from
Modules › Discussion Forum › Asite Forums › Forum Board Preferences > Topics and Post Preferences > max post per page

But it’s not working

i go through database of forum exp_forum and check column ‘forum_posts_perpage’ still i m getting old one value ‘15’

can u please let me know why this happen and solution ASAP

Thanks in advance Ankit Thakkar