What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
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.
Unfortunately it not possible to change the input type fields of just one column. You can change the matrix input type to drop down but it will change for all columns. Please check the screenshot below:
You may like to take a look at our "Configurable List" widget which should help you achieve your requirement. This will allow you to add different input types in different columns. Please take a look at the following demo form: http://form.jotformpro.com/form/41965257052962? Feel free to clone this form for a closer look. The following guide should help you in form cloning: https://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL
Please be noted that it is also possible to hide the add button by adding the custom css code in the widget. I have already made the add button hidden in the demo form. Please check the screenshot below:
Hope this helps.
Do get back to us if you have any questions.