Mezzmo may be burning the subtitles into the video when transcoding in this case, please go to the properties of the file in Mezzmo and check on the Transcoding tab to see if a transcoded file exists. You can select to 'Use Original file' from here to force Mezzmo to stream the original file to the device. Selecting the Samsung F profile with Mezzmo Android will not work as the subtitle formats supported are different so may result in subtitles being burned into the video when transcoded or not displayed at all.