I have read your description and I have done similar project before..
I am sure I am the right guy for modifying your submit button as you mentioned..
Please chat with me so we can discuss details about the project.
I am an expert in Javascript and jQuery so that won't be a problem. You can check my javascript exam score to be sure about my skills.
My profile is new in freelancer.com so I'm determined to show you my professionalism. So, please consider giving me the opportunity to work with you.
I'll give my best to earn 5-star rating from you.
I think I can exceed your expectation with my work.
I am a web developer with 3 years of experience. Worked with Html, CSS ,Bootstrap, Javascript (jQuery). I am a person working responsibly, with time availability and finish the objectives that you present, in time and with quality.
I hope you need someone like me. I would love to work on your project.