Combing Files, then something changed

[krism57716800]

Hi, I use to have no problem combing files. When I would combine them it worked no problem. Then I was trying to combine a file (.pdf's) and it said something to the effect that I had to make a change in order to combine a particular file. I clicked on the Preferences like it said to do, and I checked the box it said to do but now when I try to bring the files together and I try to combine them it turns out like this:

When I hit combine it only shows me the top file. Previously the layout was different and it would combine them as a Binder. Whatever I changed has now made it look like the photo above. I don't know what it was that I changed so I can undo that change. 
Does anyone know what to do? I hope this makes sense, and thanks in advance!

[try67 · Accepted solution]

You've created a Portfolio. You can change it back via the Option button in the Combine Files dialog:

Then set File Type as "Single PDF":

Note that you won't be able to combine files in this way if one of them is digitally signed, certified, protected or was created using LiveCycle Designer, though.

[AkanchhaS]

@krism57716800 

++Adding on to the expert's suggestion.

Here's how you can know more about the emerging files:

https://helpx.adobe.com/acrobat/using/merging-files-single-pdf.html 

Also, to know the latest changes in Acrobat Modern Viewer, you can visit this document for more details: https://helpx.adobe.com/acrobat/using/new-acrobat-experience.html 

Thanks,

Akanchha