mkv-muxing-batch-gui VS jmkvpropedit

I would recommend using a GUI for this instead. The issue with using the CLI is that mkvmerge works mainly with track ids, and I'm assuming not every single one of your MKVs are identically mapped, so accounting for all the variables just becomes too much work. Check out MKV Muxing Batch: https://github.com/yaser01/mkv-muxing-batch-gui

This tools should be able to set the default tracks in MKV files without reencoding the videos: https://github.com/yaser01/mkv-muxing-batch-gui

https://github.com/yaser01/mkv-muxing-batch-gui Today, I wanted to copy subtitles and attachments from one set of files to another.

I've resolved whit this great app: https://github.com/yaser01/mkv-muxing-batch-gui/releases/tag/2.3

I think they will only be enabled automatically if the subtitle track you want has the “Forced” flag on it within your video file. You can use MKVToolnix to do this on individual files or you can use jmkvpropedit to batch edit files.

I forgot to mention there’s also JMkvpropedit which makes it easier to batch edit. I’ve used it for anime before and it works great.

jmkvpropedit is a lovely tool that i've been using for years to do this.

JMkvpropedit

If you're ripping it yourself then your software seems to create bad metadata for your audio. You can try batch editing the audio tracks using JMKVproperedit

mkvpropedit can do this, although the command-line options aren't as convenient as mkvmerge, so I'd recommend JMkvpropedit (a GUI built on top of mkvpropedit). Should just be a case of dragging/dropping your files in then adjusting the options.