How can I format the columns of the multiple choice element?

I would like the Type of Project section of my form to be more uniform across the page.  I found where I can designate the number of columns but, how can I change the column size.

You can handle the check box options in your field with the following CSS code: 

#id_42 span.form-checkbox-item{

   width: 150px !important;

}

The given code will change the option's width, you may change the 150 value or change the height, if you want to handle the element's height then you may add "height: 150px !important;" right below the "width" property, note that you may change all the values as you want. 

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

I hope this helps.