How do I "unlock" comments?
 

I use Office 2007. I am able to add and edit comments inside cells, but after
a while of having the document open or when I open the document at a later
time, I am no longer able to edit existing comments.

How can I stop Excel from preventing me to edit my own comments? this is
very annoying...

Plesea let me know if my post is clear or if I should expand my explanation.