Here's how to get in touch with other MKVToolNix users and the developer:

• MKVToolNix community & help forum: ask any kind of question here
• Doom9's forum: in-depth discussions on video topics in general and MKVToolNix in particular can be found here
• Bug reports & feature requests: please file them over at the Gitlab project site
• IRC: we have a #matroska channel over at the Libera Chat network (I'm "mosu" there).
• Mastodon: I'm @mosu@fosstodon.org there
• If you need to, you can reach me via email at matroska@bunkus.online, but I don't do regular support via email anymore. Please use one of the methods listed above as the answers to your questions will often help other users, too.