When you compose an email, you need to be able to type the content and this occurs before the signature. If you do not have a space before the automatically added signature then you are constantly needing to move the signature down a line every time you click on 'Write'. So, by default there is always a blank line before a signature. This is by design and is common sense. Why would you have the word 'Hi' as part of a signature ? OR have you also removed the delimiters and are therefore trying to use a signature as if creating a type of template - in other words you would enter content after the 'Hi' into the middle of a 'signature' ? In order to do what you seem to be trying to achieve then you should be using an email template and not creating a signature in the Account Settings. Create an email with set up you desire and save as a template in the Templates folder. Use template when composing instead of Write.