If you have a MKV containing an x-265 video files with many subtitles and you play it as is it displays the first subtitle. Changing it while playing is a pain because the option disappear very fast. One way to do it that works with VLC in a PC is to use MKVTOOLNIX and delete the subtitles that you do not want. Also delete audio. However this does not work partially with the U1. No subtitles are displayed, but the audio does play the language you left. Strange... Detour : Get a separate subtitles file type .srt , adjust the name and add it to the same directory. Now the external subtitle plays ok. This might be a problem created by MKVTOOLNIX. I am using 9.0.1 ("Obstacles").