Contribution Report includes TIME
I took a look into this today because I thought this would be an easy fix.  It's not really.

What IS easy is to get the Receive Date to respect the Date Format settings like you describe.  If you know how to patch CiviCRM, you can find the patch I just wrote here.

However, this raises a bigger issue - there's only one Date Format for "Complete Date and Time", and most folks use that for letters to donors.  So it defaults to something like "October 3rd, 2019 11:15am".  My patch changes the report to output in this format.

However, I doubt that's what most people want from this report!  Most folks want to be able to sort by date, and changing this report would be counterproductive to them.

That leaves us with two other options:


Instead of using Contribution Details report, instead do an export of Contributions.  If you don't like the format, the Format Date Column in Extension will solve this for you.
Fix this in Excel with a formula.  See my screenshot below for an example.  My "Date Received" is column E, so I created a new column with the formula =LEFT(E2,10) in cell H2 and then pasted it down.




In the longer term, it might make sense for CiviCRM to differentiate between multiple date/time formats - one for public display, one for sorting purposes.