I logged in with my account to my PC and played for a while. Then I logged out and bought the game for my son with his account. All of my information, name and saved progress still appeared for him when he tried to play. I completely uninstalled both the game and launcher, deleted all folders related to Mojang and Dungeons from the install location, and deleted all AppData in both the Dungeons and Mojang folders. I reinstalled both the launcher and game in new locations. My saved characters and progress are gone, but even logged in with my son's account, MY name still appears, not his.

This prevents me from playing local multiplayer with my sons. Where the heck is the name being held in Windows? Is it in the registry somewhere? How do I change this so that when my son logs in, HIS name appears, not mine?