Can't insert text or graphic into PDF page that already is full of text

[Dave Cahn]

I have tried to insert a paragraph from my clipboard into a PDF document. Like most such documents, each page is full, except the last one. Nitro puts a box around each page and doesn't seem to re-flow existing text to next page (creating a new page at the end, if necessary. Instead, after I click Edit and double-click at the insertion point, I paste the clipboard contents and it shows on top of the existing text, becoming unreadable.  I tried again using Add Image with similar results, but with the image there was not even a way to finish the operation. Please tell me how to insert text or an image into an already full page.  Thank you.

I am using Nitro Pro 13.58.0.1180 under Windows 10.