Hi Don, are you composing email messages on your mail provider's website in Firefox, or are you composing messages in the separate Thunderbird program? For websites, look for a "gear" or menu button in the page and find the Compose or Write settings to edit your signature. Any luck? If not, who is the provider, maybe someone here is familiar with their setup. For Thunderbird, see: [[Signatures]]. Any luck? If not, a moderator can move your question over to the Thunderbird forum for a closer look.