Subtitles preferences are not applied until restart
In Tools → Preferences → Subtitles & OSD there are a lot of settings regarding subtitles (font size, color, effect, etc). If any of these settings are changed and saved, they are not applied until VLC is restarted. That is inconvenient, because it is really hard to set e.g. good font size when you always have to close and reopen VLC after each change. It should be applied immediately.