Windows 10 Mobile Build 10149 is quite good and stable, perhaps the first build that we recommended getting on your main devices. The build has all the basic stuff going for it. Even the “Accounts” settings now has got the ability to handle and manage your MSA (Microsoft Account), back.
As you can see in the above screenshot, accounts settings now have “your account settings” that allows you to manage the existing Microsoft account used on the device. What is more interesting though is the “Add a Microsoft account” option. When you tap on this option it takes you to the screen shown in the third screenshot. You can enter your other Microsoft account and password but then it crashes and keeps crashing sadly. So it may seem that perhaps in future builds we may see options of “migration” and addition of more than one Microsoft accounts on the same device.