Hi,
You have three good reviews there, so it seems like the people who do buy it, enjoy it.
Even the three star review is mostly positive, and having one three star to offset the two five stars is great - it makes them all look genuine. (I'm not saying they are not genuine, I'm just talking about the reader's perception when they look at your reviews.)
Cover
Strong, clear image, but you really, really need to make the text a lot bigger. Remember that a lot of people will see your book in listings
such as this. That's a tiny thumbnail, and they have to be able to read your text. Make it pop. Move the location of your name, it's obscured by the image of the Kindle. The author's name on its own looks better IMO, remove "By".
Title
This isn't catchy at all. Rework it. I know you wanted to reflect the concept of the collection, but do that in the description (although I'm not sure if that's such a big selling point, I would consider saving it for background pieces like author interviews). The title should grab people's attention. If you can't come up with anything, name it after the best story and put that first, that's what people will read in the sample.
Formatting
Your title page/copyright notice could look more professional. Have a look at some trade published e-books. Copy them. (Not all are good though, look around - or take a look at the sample of one of my books in the signature.)
Also, you have some blank pages at the start - remove them - it looks bad, and it means that the reader gets less of your story to sample - you want to give them as much as possible. On a similar note, your title page seems to run over two pages - remove the space at the top and try and get it onto one page.
Another thing - you seem to use a long line of dots as a scene break. Either use one clear line or three stars centered - ***.
Finally, you have gone for "block text" formatting which is more common for websites. Consider going with a more traditional way of rendering the text - look at printed books and some of the bestselling e-books - copy that.
Sample
I haven't read the sample, just glanced over it for formatting issues. Make sure you are starting with the story that has the strongest opening, that will make people want to buy the rest.
Marketing
It's hard to give you advice without knowing what you are doing already. Are you on Twitter? Facebook? Goodreads? Do you blog? Have a website? Have you sent your book out to any book blogs?
Amazon Author Central
It looks like you haven't set this up, it makes your book listings look a lot better, and you can link it to your Twitter account and your blog. Go here:
https://authorcentral.amazon.com/gp/landing?ie=UTF8&*Version*=1&*entries*=0
Dave