Edit FOnline2238.cfg in section 2238 paste it:
ScreenshotName=screenshots/%CHARNAME% lvl_%CHARLEVEL% %DAY%-%MONTH%-%YEAR% %HOUR%%MINUTE%%SECOND%.jpg
LogfileName=logs/%CHARNAME% %DAY%-%MONTH%-%YEAR% %HOUR%%MINUTE%%SECOND%.%EXTENSION%
You can custom it like you want.