The problem is that I would like to make a selection on a track group and the programe important to me in a different txt file for each track. Can you help me? Thank you.
There is no built-in automatism in Mp3tag for exporting text into several files for each selected track separately. But there are two tools to circumvent this barrier.
After installing ... try out the offered example Mp3tag export ".mte" scripts, ... they should be listed in your Mp3tag Export dialog.
At first you may have a look into the ".mte" files and their coding, ...
and decide which one could be used right away, ...
or perhaps has to be adjusted to your personal needs.
Try out the work routine with a few files, which have a tag-field UNSYCEDLYRICS filled with any text.