Ok - I was looking how to sort by popularity and found this thread. This is how I would sometimes find the right song, I wanted to purchased. Now it seems that feature is not available on the "main" page. However I found that it is available on a song page.
For example I was looking for a song by Audiomachine. Could not remember the title. Typed in Audiomachine to the search in the store.
It brought me to a page that had results and to the right was a side bat listing ALL, SONGS, ALBUMS and then below that another sidebar ARTISTS & MORE which had listed AudioMachine/classical and Epic Symphony/world.
I attempted to sort the music that was listed by popularity trying the old way by clicking on the word popularity. That did not work.
I finally clicked on the Artists & More listing of Audiomachine/classical. Which took me to the page with all of the albums listed. At the top of the page is ALBUMS. And there are thumbnails of the albums. Scroll down below to SONGS
Next to the word is Best Sellers and the tiny arrow. click on the arrow and it drops down to give you the option of sorting the albums by Best Selling, Name, or Release Date.
If you click on Best Seller. Look to the right and click SEE ALL.
Then you will see the songs listed by popularity.
Yeah - seems like a long way to go now to do something that took maybe a few moments before. Hope this might help sorting for other things.I think you would just do a similar action.