Reordering editions to show newest first

[Elizabeth]

I've just added a new edition of my first novel, Alliances, published this year by Straight Up Press. Then I combined the 2010 edition with the 1987 edition published by Worldwide Library. However, the cover image for the combined editions is the 1987 cover, and I think the 2010 cover is more appropriate. However, I have no clue how to make the change. Please advise.

[Melody]

The most popular one shows up first. Since someone has market the 1987 edition as one to read then it shows up first.