Are you using the Edit Text & Images tools? Because what you're describing are not text fields, but text "boxes".
If that's the case the answer is no, you can't tell the application to merge or separate them.
Yes i use the Edit Text & Images tool from Acrobat Pro DC. I do not know the exact name of this text areas, but you could be right: text boxes for putting text in the document.
At the moment the application automatic merge these areas to one at saving. Thats a big problem for me, because i want to format each text box individually and not let to merge them.
PDF files were never meant to be edited in such a way... If you have the
original file used to create the PDF you should edit it and then generate a
new PDF file from it.
That's a much better workflow.
I am using Acrobat XI.
I have similar question but a bit different question.
Is there a setting /program option that allows the user to turn ON /OFF that reshaping of the boxes? In my case after saving and reopen the file, the boxes are changed in a way that a sentence is now contained by multiple boxes. Amazingly, frequently they are broken into weird pieces: the left part of a paragraph and the middle or right part of the sentence are boxed separately of the left box. This makes IMPOSSIBLE to change a sentence, forcing my to rebuild the original sentence or mathematical formula by copy and paste in a single box. I HATE THAT WASTE OF MY TIME!!!!
No, it's not possible.
The reason is that PDF files were never meant to be edited in such a way! Hence the great difficulties in doing it... It's simply not the way it's supposed to be done. You need to go back to the original file, edit it and then generate a new PDF file from it.