JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
You can center your submit button inside of Form Builder. Simply select your submit button and set Button Align option to Center.
Currently width of your form is set to 1300px.
You can change the width of your form and make is less wider by changing the width value 1300. You can reduce the width to 1200px. If you reduce the width more then some field will be outside of the form border and code that my colleagues provided you on your other thread will need to be changed.
Hope this will help. Let us know if you need further assistance.