Could you explain this in depth?
It's mostly subjective but I'll try.
The primary color of your app is orange, with accents of blue-cyan, magenta, and purple. Not only do I think four hues is much in a color palette, they also clash in a strange way. The harmony between orange and blue-cyan works because they are complementary colors. The addition of magenta (and purple), however, creates a clash that makes the colors not work as well together. Both colors are between Magenta and cyan CAN work together, but the orange would have to be more yellow.
I, however, think the orange is a good color for your primary and should stay. I made a test palette for myself and tried changing the magenta into a more pleasing color and the blue-cyan to something more cyan. I went with a split-complementary palette and tried changing the magenta to a blue. The buttons' colors create contrast from the background, but are still close enough to the main color that they draw attention to themselves.
Another solution would be to change the magenta to red, but red tends to be a very strong color and might overpower the orange background.
As for the purple, I would say eliminate it and replace it with the blue color (or if you still like magenta, use that). 3 colors is enough in my opinion. Always remember, though, that your opinion counts more, so go for your four colors if you like that better! :)
