to default songs you would first have to become an editor for a band. Then you can sort the albums and songs out.
You can hide all the " best of" albums as the songs will be on other albums, then you can hide songs making the one you have corrected being the only song for that album.
Other than that you would have to just click on the bottom of the song to correct it, but it would not make it the default song. Most people I would think will click on the first version of a song being at the top of a list so maybe your best bet would be to correct any at the top of a list.
As chordie does not host the songs it cannot automatically default the songs. You could go to the priginal site it came from and submit all your corrections to them and then once the yare on the site that hosts them then you can add them to chordie's index, but I suspect that would take ages.
Sorry I have no simple answer for you