If there is special setting e.g. special offer/early bird for special days, you need to set by override.
1.Special offer for a certain day e.g. $ 500 for 5 Jan adult lunch instead of $ 699
Select [Override] > [Create by date]
For example 5 Jan is booking date
2.Select 2017-1-5 for Booking After % Booking Before field > click [Create] button
3.Click [Edit] button > edit required setting (price, discount, quota etc.) > [Save] button
4.Price updated to 500 for 1 Jan
5. [click to leave override] > continue other settings