Hey, I had this problem on my iPad and fixed it. I changed my kid's settings on xbox.com and when we tried to load Minecraft it would crash when signing in. The solution was to first turn off internet access (flight mode easiest, turns off data access too if you have that). Then open Minecraft. Let this run its course, it'll try and fail to sign in. Then go to settings and then profile, where you can sign out of xbox. That'll pop up a secondary window to confirm signing out. On my iPad this can be slow to happen (taking seconds) so bear with it. Once you are signed out, turn off flight mode and then sign in (from the profile window where you are/were). This process takes you to browser and online to sign in. Sign in with your kid's account, and that will then go back to Minecraft and all should be well!
Rick O'Gorman
Hey, I had this problem on my iPad and fixed it. I changed my kid's settings on xbox.com and when we tried to load Minecraft it would crash when signing in. The solution was to first turn off internet access (flight mode easiest, turns off data access too if you have that). Then open Minecraft. Let this run its course, it'll try and fail to sign in. Then go to settings and then profile, where you can sign out of xbox. That'll pop up a secondary window to confirm signing out. On my iPad this can be slow to happen (taking seconds) so bear with it. Once you are signed out, turn off flight mode and then sign in (from the profile window where you are/were). This process takes you to browser and online to sign in. Sign in with your kid's account, and that will then go back to Minecraft and all should be well!