Please open "Tools-Preference" and select "Automatically rename as " there. Generally, it is the default option. For example, if your file is called "audio.wma" and you want to convert it to MP3 format, after the first conversion job, the output file will be named as "audio.mp3". If you do the same conversion job again, our program will generate a file, called "audio-0.mp3". And also, if you perform a third conversion, the third output file will be "audio-1.mp3". It means it will produce files in different titles each time in this way.