Why is Subtitles Forced only greyed out?

[DocJellyBean]

As soon as I select a subtitle track, the Forced only checkbox is greyed out. The Default (which is what I want) and Burn in boxes are active. It seems one can't disable Force only.

[RandomEngy]

Some combinations of subtitle type and container don't allow "soft" subtitles, you have to burn them in. This is the case with PGS subtitles and the MP4 container.

When the only supported option is burn-in, VidCoder disables meaningless options like Default and restricts to 1 track in the output.

You can try switching to the MKV container.