can not change fields in pdf

I have pdf files that allow changes to certain fields.  Following the recent update to the Acrobat Reader DC program, I can no longer change those fields.  I loaded a file on my computer from a friend's computer onto my computer and I can not change it either.  He is able to change it on his computer. Does anyone have any idea what may be preventing me from changing the editable fields in the pdf files on my computer?