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

JabRef version JabRef-4.2-dev--snapshot--2018-02-04--master--6bac6ff2f.jar

Steps to reproduce:

1. Select some entities
2. Export selected

The last used type for export is not remembered and in case of overwriting the old file the confirmation is asked two times.