In Windows 8 or later editions, many a times you need to use your Microsoft Account instead of a local account, for example, while using the Windows Store. So for this you have to switch to Microsoft account from the local account. For some, it goes fine while for others it become the matter of trouble. Suppose you upgraded a system from Windows 8 to Windows 8.1 by using Microsoft account on your system. Now after the upgrade you may came around following error:
We’re sorry but something went wrong. Your account wasn’t changed to this Microsoft account. Code: 0x80070426

When you get this error, first of all simply reboot. Another things you can try here to set up new user account and switch it to Microsoft account. But if you’re the one who don’t want to setup new user account and then switch to Microsoft account, you can try following steps. We suggest you create a System Restore point before proceeding.
Your Account Wasn’t Changed To This Microsoft Account
1. Press
Windows Key + R combination, type put
regedit in
Run dialog box and hit Enter to open the Registry Editor.

2. Press
Ctrl+F and type your
Microsoft account email ID, for example yourname@outlook.com or yourname@live.com. Make sure you’ve
checked options
Key,
Values,
Data. Click Find.

3. The result will come around these two registry keys:
HKEY_USERS\.DEFAULT\Software\Microsoft\IdentityCRL\StoredIdentities
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\IdentityStore\Cache\GlobalStore\IdentityCache\S-1-11-96-3623454863-……..
I have shown one entry in below image. There would be only one key with this long name for which the email ID you have entered in
Find box will matched, so not to be confused at all.

4. After finding both the above mentioned registry keys, export them at a convenient location and then Delete. Close the Registry Editor and reboot the machine to get fixed.
Your problem should be resolved.
twc