Will changing my MC username mess up my rank?

[Smudge]

I'm thinking about changing my current Minecraft username (thatrandomguy24) to something different. I also purchased gold rank on CubeCraft. Are the ranks assigned by username or UUID?

 

[Buuuddy]

Ranks are assigned to your UUID. Your UUID never changes so you can safely change your username without loosing your rank. :)