How do I add a second element or box to a particular line?

I would like to add an additional element or box to a particular question (i.e. http://screencast.com/t/is5bwLepHNn) 

Please refer to our field positioning guide: https://www.jotform.com/help/90-Form-Field-Positioning.

You have the option to merge a field into above line or move down a field to another line. Also, you need to consider the form width. You may need to adjust it for three to four columns to appear:

https://www.jotform.com/help/35-The-Importance-of-Form-Widths

Lastly, you can make a perfect column in the Form Designer (https://www.jotform.com/form-designer/). In the Form Layout tab, enable columns and set the number of columns:

Thanks