saving file with new TITLE to existing directory

I just recently acquired mp3tag. I have managed open the related directory there and update all TITLE's so TITLE=%_filename%, however I cannot save it in existing directory.
I need it as , my car mp3 player looks for file TITLES, but understand only MP3 format
please advise

I do not understand your problem.
If you open a file and edit the tags, the new information is saved in the files automatically if you edit the files in the files list.
So if your files were good enough for the car stereo before you edited them, then nothing has changed.
Or do you want to move the files to a specific directory?
Or have you edited the TITLE and now you want to update the FILENAME?
See the Convert>Tag-Filename function for this task.
If all this is wrong then please describe your problem with examples like "before" and "after".