Administrator wants to make ALL new posts appear at top of ALL forum pages. How?

[building]

I want to make all forum pages have the new posts at the top. Right now it has the first post at the top but I don't want it that way. I know that each user can go into their profile and choose that option, but I want as a default for all new posts to be at the top. Can anyone help me with this?

[metallica48423]

Reset theme options for all current members:
admin > current theme > reset options > Reset all members' current options for this theme

reset theme options for new members:
admin > current theme > reset options > Reset default (guest) options for this theme