If someone else uses your signature without authorization, you don't have to bear the legal responsibility of signing, and the responsibility of signing is borne by the actual signer.

general rules of civil law

Article 66 An act without agency, beyond agency or after termination of agency can only be ratified by the principal, who shall bear civil liability. If the act is not ratified, the actor shall bear civil liability. Knowing that another person has committed a civil act in his own name without denying it is regarded as consent.