JabRef 5.0--2020-03-06--2e6f433
Linux 4.9.0-12-amd64 amd64
Java 13.0.2

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

In Library > Library properties, the export sort order can be specified.
However, the choice is not memorized.
Steps to reproduce the behavior:

1. Open a library
2. Go to Library > Library properties
   In my case, the sort order was:
   
3. Change the sort order
   Like:
   
4. Click on OK (closing the Library properties window)
5. Go (again) to Library > Library properties
   The initial sort order is displayed: