Embedded note

I am note sure what to call this feature of excel, but an embedded note is the closest I can think of.  

I have inherited a spreadsheet (being used as a form for others to complete) and need to update it - it does not appear to be protected at all, or at least I think I have unprotected anything that was.

When certain cells in the sheet are clicked on, a yellow note appears (see screenshot).  It is not though a note in the sense that there is a small red triangle and a text box that can be clicked on to edit the note - these just appear and cannot be edited at all.   It is some sort of embedded instruction that is now out of date or plain wrong. 

I cannot find any way to 'un-embed' or 'unlock' these notes though - I can change the text and formatting of a cell, but the note does not alter.  I can copy and paste the cells, and the note goes with it (unless I use paste special and only paste the text, but then that means I have to reformat the entire thing!).

If I knew what this feature was called I would be able to look it up to find the solution.  But I can't find a name and I can't find any way to remove or edit these notes.  Help!