hello, once i've muxt a .srt into an mkv file i am unable to edit it. if i open the muxt mkv file and remux with just the subtitle to an mks and rename it to srt i am unable to edit it. i also dont know software which allows me to edit mks files despite googling a few times.

You need to extract the subs from the MKV in order to edit...Use MKVExtractGui, which comes with MKVtoolnix and extract...Do your editing and then mux back with MKVmergeGui....You can google MKVExtractGui...