So, it can be understood as I can't edit my pdf file..?
I tried to click on save or save as, but apparently it didn't save the file on my computer, and I don't know why this could be.
When I clossed adobe it just kept asking whether I need to save it before I close it. But it still didn't work either I pressed Yes and select the original file name to overwrite it or to find a new location and rename it.
What I did to edit on the file is just highlight some sentence or put a comment on it.