Windows 10 makes it easy to add the accounts you use for your apps in one place in Settings > Accounts > Email & accounts so you can sign in to your favorite apps easier and faster.
When you add an account in this central location in Settings, that account will be a listed account available to select to sign in to an app with. This can be handy so you no longer have to manually add the account for each individual app you want to sign in to with it.
This tutorial will show you how to add and remove accounts used by other apps to sign in with for your account in Windows 10.