How to have the description field extend ?

I would recommend you to inject the following CSS code to your form in order to get the description field extended: 

.form-matrix-table tbody tr:not(:first-child) td:not(:nth-child(2)) input{

    width: 500px;

}

This guide will help you injecting the code to your form: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes  

Here is an example about how it will work: https://form.jotformpro.com/72275332154957 

I hope this helps. 

Your form looks great. But im not sure how to get it in my signon.

...

I believe I have already addressed your request in the other thread you created: https://www.jotform.com/answers/1225222

But it doesn't hurt to repeat it here for your convenience, so here is our guide on how to inject your custom CSS code into your form: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

I hope this helps. If you need further assistance please let us know. Thank you.