Not really a troubleshooting problem... but something am confused about.
I looked in the settings and found that the subtitle move up/down hotkeys were blank.
However, magically, I found that they are already set to ARROW UP / DOWN.
I also could not find in the settings for hotkeys for subtitle sizes... but I magically found that CTRL+NUMPLUS/MINUS works.
Maybe someone else verify these 2 very useful shortcut keys are working.. and maybe need to make it consistent in the hotkey dialog?