Strange, I don't see it either.
In baseball & hockey pools, you:
Click "League".
Click "Scoring & Settings".
...and then it is under an area called "Weekly Deadline".
And that will say something like "Daily - Today" or "Daily - Tomorrow" or "Weekly - Sunday"... something like that.
I don't see it for football leagues either.
Strange.
Perhaps Yahoo! doesn't have a lock for roster settings in football.