UBB.threads PHP Forum Software Community Forums UBB.threads 6 Version 6 Support Number of threads per page, displayed

newbie question: When users login for the first time, their prefs are defaulted to 10 topics per page.
Where might I change that?
Is it in edit/config/ or theme settings?
I see one that says:
Default Textarea rows
and it is set for 10.
Might this be it? If so, why doesn't it just say so?

Jen