I can not turn on the quantity selector?

I can not turn on the quantity selector? Thus I can't use the above example?

Just to confirm, we are talking about this form: http://www.jotform.us/form/72684700884162 right?

I see you have enabled sub products from options on your customize option: 

but you have already enabled special pricing per option for Size:

Which results in this:

The solution is to remove the customize sub products option. And create a new product under it called "Customize" for each product. Now your customize options will be added to the total. 

Note you can simply duplicate them if you click on the gear icon.