Accepting / Declining a reservation

Hello,  I am new to booking.com.  I have failed to find the setting to turn instant booking off and rather go on a manual option to accept or decline a reservation.  Booking.com does not properly sync calendars to other rental platforms, so there is always a gap and I find it difficult to manage when the property is already occupied and you get a booking on Booking.com  Please assist with this?  It creates a lot of additional admin.

Thanks

Abbey