Hi,
The default primary ordering is by “relevance”, which is basically keyword relevance, and therefore it has nothing to do with the post dates. If newer results are priority, then I would first suggest changing the primary ordering by publish date and the secondary by relevance: https://i.imgur.com/7QZ0D2W.png
That will always display matches within each group ordered by date first.
If you want to prioritize custom field values over other fields, then you can adjust the relevance values for that here: https://i.imgur.com/0MzyF2N.png
However the relevance will not matter much if the primary ordering is by date descending.
Suggested Results Do Not Respect Custom Relevance Logic or Grouping Expectations
I need much more details on this to be able to help. Can you please elaborate which results are not as expected exactly?