Select Unfold in the Fold menu to unfold a section previously folded with Fold|Fold. The Unfold command only becomes enabled when you’ve placed the text cursor on the first (still visible) line of a folded section. The unfolded section remains marked as a folding point, so you can easily re-fold it.
If you’ve made a selection, then all folding points inside the selection are unfolded.
Use Fold|Remove Fold to unfold the section and remove the folding point at the same time.
If the current file type uses automatic folding points, then unfolded ranges automatically disappear when you edit the file. They are replaced by new automatic folding points that may be the same or different, depending on how your edit affects the file. Folded ranges remain folded until you unfold them.