How to select and duplicate all the questions of one page?

I have multiple pages, each with more than a screen-ful of questions.

I would like to duplicate all the questions on one page. When I try to scroll when selecting, nothing happens.

I also tried reducing the screen magnification to 25%, but that still only gets half of the questions on the screen.

I am not sure if I have understood your question correctly. Do you mean to say that you want to select multiple questions of one page and duplicate it?

You should be able to select the questions and scroll webpage to see the remaining question which you can select. I cloned your form and I was able to duplicate forms fields without any problem. I was able to select form fields, scroll form and select more form fields. Please check the screenshot below:

Do you mean to say that when you select form field, you are unable to scroll form down to select more form fields?

I would suggest you to please try again and get back to us if you have any trouble. 

I'm sorry.  I was not clear.  I see the misunderstanding.  

I was trying to select via drag selection, vs. clicking the boxes individually.  I was doing it that way, b/c if, after selecting 20 boxes, I click wrong, I might LOSE all my other selections.

Thank you for clarification. From what I understand is when you select multiple fields you can not drag/move them. When you try to drag them nothing happens.

If this is the case then this is true when you select multiple fields you can not drag them but rather you can perform some actions to them like delete, duplicate hide and Unrequire the fields.

You cannot move the position of the selected fields.  in order to move the fields you will need to move one field at a time by dragging them to the required position.

No, not drag AFTER selecting, but "I was trying to select via drag selection, vs. clicking the boxes individually" to select multiple boxes.

How do I select and duplicate all the questions of one page? via select via drag selection, vs. clicking the boxes individually?...when the questions exceed the extent of the visualized screen?

Unfortunately its not possible to select multiple fields in order to manage the selected field. You will have to either select the fields individually or select all fields in the form.