Minecraft – My Minecraft skin will not change

First make sure that you're logging in with your email address, not your old Minecraft username. Everything uses your email address now that you've migrated your account.

If that's not the problem, this is simply an account bug that we can't help with. For account migration issues that aren't resolved by that help article, you need to contact Mojang support as it says at the bottom.

(No, accounts can't be un-migrated.)

Here are eight possible reasons why your skin isn't showing:

1. Your skin has not refreshed yet. (If you're playing Minecraft 1.7 or above)
2. You never had a skin prior to the UUID update, which changes the way skins are stored (If you're playing any versions prior to 1.7)
3. You're not using a legal version of Minecraft, and therefore - Your skin isn't registered to your account.
4. The server you're playing on has online-mode=false. (Set to offline mode; no authentication)
5. You changed your char.png file within the minecraft.jar and not uploaded it to your minecraft profile.
6. You've uploaded it to your http://minecraft.net profile, but it's the WRONG dimensions (bigger than 64x64 pixels)
7. You're playing in offline mode.
8. None of youse have an internet connection.
9. You may have a bad internet connection and thus timed out or received incomplete information.

For #1, you'll just have to wait, and/or restart your game.
For #2, there's nothing you can do.
For #3, buy the game!
For #4, you should consider playing on servers that only allow 'premium'/paid users.
For #5, you should probabally log into http://minecraft.net.
For #6, you'll have to scale it down. Sorry :/ Unless you get the HD skins mod.
For #7, go online!!! (Same goes for your brothers)
For #8, you'll need to be connected to the internet in order to retrieve skins.
For #9, nothing I can say apart from the generic "get better internet" or "clear off your bandwidth by downloading/uploading less (ie. Stop watching YouTube on 4K whilst others are gaming)".

Very likely, based on the information you've stated that your problem is #3.