Where's the difference

I open a pdf file in a directory on my Samsung tablet using a file manager app.   It's a fillable pdf, i make changes and exit via the back button and acrobat saves changes to my original file.

I do the same on my note 5 and acrobat males no changes to the original file but leaves a new copy in the recents tab in acrobat.

Where's the difference?  Why does one behave differently than the other?  What am i missing?