Is there a app that would change the colour of my hue lights
Can you supply more details? Do you want to change it manually or have it change based on some other action like motion, contact sensor, etc…?
Want to to change to a random colour or cycle though colours
You can try this.
The easiest way is probably to use the Phillips hue IFTTT channel. You can trigger it from echo or from SmartThings turning on a virtual switch.
It has both color loop and random color options:
You would need one recipe for each bulb, but you can have the same trigger fire multiple recipes.