Hi Ross
I'm enjoying your series on self-publishing - thank you for sharing your experiences with us!
I hadn't heard of Pixlr X before, so I will check it out! I have had a go at using Amazon's Cover Creator tool but I found it had a lot of limitations. I then used Canva and created a better cover but it wasn't really the one I had envisaged - I had to compromise!
Many of my clients have been very happy with the book covers designed for them by graphic designers but I think you need to find someone you can communicate with and who is willing to do a series of designs to discover what you really want (often, you don't 100% know yourself!).
Thanks again for your contributions Love Self-Published Books,
Roz