help for subtitles explanation

Hello Guys,
I'm a little bit confusion with subtitles options.. anyone can help me to undestand the 3 flag and the preferred language option:
1. Enable Subtitles (is it for the extrected .srt from the mkv??)
2. Enable Extraction of subtitles embedded in video files (This is for the embedded subtitles, but many times it choose the wrong subtitles for example the director's commentary?)
3. Enabled burned-in subtitles (I haven't undestand this option)
4 Preferred language (How I can recognize the right subtitles with mkvtoolnix and put the righ string for the subtitles?) for example if i put in the preferred language space "ita" serviio choose the directo'r commentary in italian language, but if i want to see the italian forced subtitles how I can do that?
See the screenshot
I hope anyone can help me
Thanks in advance
I'm a little bit confusion with subtitles options.. anyone can help me to undestand the 3 flag and the preferred language option:
1. Enable Subtitles (is it for the extrected .srt from the mkv??)
2. Enable Extraction of subtitles embedded in video files (This is for the embedded subtitles, but many times it choose the wrong subtitles for example the director's commentary?)
3. Enabled burned-in subtitles (I haven't undestand this option)
4 Preferred language (How I can recognize the right subtitles with mkvtoolnix and put the righ string for the subtitles?) for example if i put in the preferred language space "ita" serviio choose the directo'r commentary in italian language, but if i want to see the italian forced subtitles how I can do that?
See the screenshot
I hope anyone can help me
Thanks in advance