Automated e-mail with use of individual signature

Hi there,

I am setting up an automatisation flow with e-mail for new leads which can be triggered by everybody. In the e-mail settings in the Send Email with Template, I have clicked of the signature box  (Use Signature: Yes). The flow works when I create a new lead with my signature. However when my college creates a new lead, my signature is used, not his. 

How can all users have their own signature on the e-mail?