•Enable burned-in subtitles: Enable or disable burning in external subtitles (SRT, SMI, SUB) on top of the video.
•Subtitle language priority: Subtitle files can contain a language specifier in their filename in one of the following forms: "movie.en.srt", "movie.eng.srt", "movie-en.srt" or "movie-eng.srt". Where "en" or "eng" can be the two or three-letter ISO language codes. Languages should be entered using their three-letter code, such as: "eng,rus,ita". This will try to find an English language subtitle and burn that first, if that fails, it'll try to find Russian and then Italian. If none are found or recognized, the first external subtitle will be delivered (if there is any). If you are not sure about the correct code for your language, please ask on the forum or contact support.
•Font name, size and color: You can choose any of the available fonts and make it a certain size and color. You can choose smaller fonts for larger TVs and larger fonts for smaller TVs to make reading easier.
•Encoding: Allows you to set the code page that should be used when loading and rendering subtitles for this device. Some common code pages can be found here: http://en.wikipedia.org/wiki/Code_page
•Scale: Allow you to adjust the size of fonts in external subtitles that were designed to be a certain size and where multiple fonts are present. This keeps the same relation between existing font sizes, but lets you adjust the subtitle size in general to make it easier to watch on your device.
You can use the Generate Font Cache button to regenerate the fonts cache. This should be done if you add/remove fonts on your system.