If multiple Minecraft usernames log in via the same computer user account, they will be able to access each others' saved worlds. You can change this, though it requires a bit of advanced setup. To keep things clear, the following three terms are used:
- Minecraft username - This is the name of your Minecraft character that your account uses.
- Computer user account - This is the computer account that you log into when you start up your computer.
- Minecraft launcher configuration- You can make Minecraft run with different settings or in different versions by using different configurations, accessible from the Minecraft launcher (before you press Play). By default, most users will have a single configuration called "Latest Release", but you may set up any number of configurations.
Windows (Java Edition)
You can have Minecraft create world saves and player data in a different location than the default. If you do, you will not see the worlds of others who use the same computer. To edit create a new launcher configuration:
- Run Minecraft
- Go to "Launch options" and click "Add new"
- Switch on the "Game directory" option, then specify a different file path (for example, C:\Users\Steve\AppData\Roaming\.minecraft to C:\Users\Steve\AppData\Roaming\.minecraft2)
- Click "Save"
Windows 10 Edition
Besides changing the file path, you can also just create a different computer user account.
- Click the Start button, click Settings (cogwheel), go to Accounts, and then press Other Users.
- Click Add someone else to this PC and fill in their information. You can choose to create a user with a Microsoft account or make a local user without an account.
- Do not use an exclamation mark or Minecraft will not run
For more information, please visit the Windows help site at https://support.microsoft.com/help/4026923/windows-10-create-a-local-user-or-administrator-account
To create a new computer user account on a Mac:
- In Users and Groups preferences, click Add (+) below the list of users
- Choose the type of user you want to create from the New Account pop-up menu
- Type the full name for the new user. An account name is generated automatically. To use a different account name, change it right away since you can’t change it later
- Enter a password for the user, then enter it again to verify. Using a password hint is recommended in case you’d ever forget your password
- Click Create User
For older OS versions, please see support.apple.com/kb/ph6651
To create a new computer user account on Linux:
- Open the terminal.
- Copy and paste: useradd -m -s /bin/bash Your_username
You need to be an administrator to create a new account. The procedure of adding new users to the computer can be different depending on the distribution and administration settings. Please refer to your operating system documentation for details on how to create a user profile.