Here is a guide to changing your name in minecraft . First you log in on https://minecraft.net , Once you done that click profile https://minecraft.net/profile . And there it says To change your settings, go to your Mojang account settings page click that https://account.mojang.com/login . You need to login on your mojang account first. If you do not have one yet you can just make one. Then you need to Migrate your Minecraft with your mojang account. Once you have done that there is something like this YourIngamename(Change) and you click that. But be aware If you change your name now you have to wait 30 days before you can change it again, so choose wisely! Hope this Helps!

-Diaxy