General Options -> Ordering
On this options page you can change the individual and mixed result ordering.
General Options -> Ordering -> Result Ordering
This option will change the ordering of items in the same result type group. Default is "Date descending".
Also note, that this is only a secondary ordering, as Relevance is the primary. You can disable relevance ordering on the Relevance Options panel.
When choosing Custom field based primary or secondary ordering, two other fields will pop up:
Custom field name - The name of the custom field.
Type - Numeric or String (date type fields will work with both options)
This list will contain some of the most used custom fields, use it in the 'custom field name' section.
WooCommerce price fields: _price, _sale_price, _regular_price
The Events Calendar dates: _EventStartDate, _EventEndDate
Events Manager dates: _event_start, _event_end
By default all post type results (posts, page, products etc..) are ordered as one group, regardless of the post type itself.
If you want to prioritize certain post type over others - for example display product results first, then posts, pages etc.. - then make sure to enable post type group ordering:
General Options -> Ordering -> Mixed results order
If more than one result type group is active then you can order these groups here.
For example you have a search configured for Posts and BuddyPress activities. You want the BuddyPress Activities displayed first. In this case you will need to drag the "bp_activities" item above the "post_page_cpt" item:
terms - categories and terms
post_page_cpt - posts, pages and every custom post type
blogs - blog results (blogs as result)
comments - comment results
bp_activities - BuddyPress activities
bp_groups - BuddyPress groups
bp_users - BuddyPress users