how to export the audio without video as ringtone

Export specified Audio Channel only

switch and create new project, because we just do cut so settings are doesn't matter, just "OK".
then add the the movie or video file to layer.
or drag the file to v2mixer's layer
click "Cut" (the scissors icon)
switch to "as New file"
select one of "audio Track" you want to use for ringtone.
keep codec as "copy"
select(the dialog left bottom) the file where you have to save.
click "Queue" submit as job
wait the job done. (the clock icon in top main bar, name "Queue", or just wait it will flashing prompt you when done)
you will see the file in the folder you selected.
1. click the info icon in the Queue list, will open the file manager for that folder
2. for example you export only audio with aac codec, will got aac file in folder
now we have the specified channel's audio file without video, we have to export as marker A to B to get part we want as ringtone.