To set up a separate email signature for replies and new messages, follow these steps:

1. Create two separate signatures
2. In your email application of choice, set your default signature to the one you wish to use for new messages
3. Navigate to the email settings and locate the reply with option
4. Select separate signature to enable two different signatures for new messages and replies
5. Activate your second signature for replies

Now, you will observe that new messages are created with the default signature you have set, while replies will display the alternate signature.