Go to the Subtitle menu, click on Sub Track and choose English (or the name of the language your subtitles track is on):
If you want to make the subtitles show by the default, then go to the Tools menu, choose Preferences and click on Subtitles & OSD. On the Subtitles Language tab, next to Preferred subtitles language, write the name of language you want to make default. E.g., if you usually display English subtitles, then write English. Then click Save. Next time you open VLC, you should be able to see subtitles automatically.
Appearance Settings on VLC:
On VLC, some appearance settings can be changed under Tools -> Preferences -> Subtitles & OSD. These include Font, Font size, Font color, Background color (named Effect on VLC Windows, and Outline color on VLC Mac), and Vertical placement, on VLC Windows (named Force subtitle position on VLC).
For the changes to take effect, you need to click Save, exit the player, and open it again.