These are visible in Tools > Options > Load/Save > General > 'Always save as'

Change-Id: I879200a535b46b54653c9e0947a2e8064c72ac91
Reviewed-on: https://gerrit.libreoffice.org/45543Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Andras Timar <andras.timar@collabora.com>
(cherry picked from commit 1764c035)
Reviewed-on: https://gerrit.libreoffice.org/45699