To set up a Temu sub-account, you need to follow the steps below:

1. Open the Temu main interface.

2. Click the drop-down arrow next to the user icon in the upper right corner.

3. Select "Settings" in the pop-up menu.

4. Select the "Account" option in the navigation bar on the left side of the settings page.

5. In the account settings page, you can do the following:

- Log in to an existing account: If you already have a Temu main account, you can enter your account and password here to log in.

- Register a new account: If you are a new user, you can click the "Register" button to create a new Temu sub-account. Fill in the relevant information as prompted, including username, password, email, etc., and then click the "Register" button to complete the registration process.

- Switch accounts: If you are already logged in to an account, you can click the "Switch Account" button and enter a new account and password to switch.

- Logout: If you want to log out of your currently logged in account, click the "Logout" button and follow the prompts.

Please note that Temu sub-accounts are associated with Temu main accounts. You can use sub-accounts for games, social networking and other activities on Temu, but some functions and permissions may be restricted.