I've upgraded to V15 and want to retain formats of dates & times from previous version.
I've added
NLS_DATE_FORMAT=dd-Mon-yyyy
NLS_TIME_FORMAT=HH24:MI:SS
to the params.ini file
and amended the NLS Options in Preferences to match these as "user defined"
but - grid date/time is gobbledegook, for example, "23-9o19-2022 1124:19I:47"
I've tried all apparent combinations to no avail - what am I doing wrong?

Solved!
In the Preferences for User Defined dates & times you need to use Windows formats (not Oracle).
So date is dd-MMM-yyyy and time is HH:mm:ss