why can't my columns go full width

Are you referring to this form? (http://www.jotform.us/form/60437625159156)

To adjust the width of your field, simply follow the steps below:

1. Click on the single column field

2. Click the Size button on the menu

3. Input the new width of the field.

Here's the screenshot of the field where I applied the size 80 to the E-mail field of a cloned form.

You can check out the cloned form by following this link: https://form.jotform.com/60450741915958

If you want to clone it, then you can simply follow the instructions in this guide: How to Clone an Existing Form from a URL

Do let us know if you need further assistance.