Select Call distribution groups or Voice responses (depending on which you want to edit).
Choose the groups you want to schedule (if you want to make a change for all of them, press the box at the top left).
3. Click on the "Pencil" .
4. Click on "Edit schedule" down to the right.
Here you'll be able too adjust the dates, times, actions and prompts.
Just remember to hit "Save" when you're done and you'll be all good.