While the fill and sign function has the wonderful option to sign from a mobile phone (using the fill and sign app) - it doesn’t have an option to protect the signature with a password. Luckily the “certifications” function has a digital signature option that IS protected by password, however unfortunately there is no way to use this function from a cellphone - only from a computer , which is a shame. Many people prefer to quickly and easily sign things on the go using a cellphone, while protecting their signature with a password. some food for thought. Thanks