Samsung S4 signature wont turn off

[Ella4881]

I have a Samsung galaxy s4 and the signature wont turn off. In the options it does not show a signature being on. When I send an SMS the recipient sees a signature of "YesIdo" but I do not see it. I downloaded AVG and Avast neither caught a virus. I factory reset the phone and it still shows up. How can I get rid of this?