Problems editing an existing pdf

Sometimes when trying to edit or specifically change the color of text in an existing pdf, I get an error message saying "this document restricts some features of Adobe Acrobat DC..." and asks me to save a copy.  That doesn't work either.  We previously owned a copy of Adobe Acrobat Pro, but replaced it with the cloud version.  I never had this problem before, and my job requires occasional font color changes of some items in a pdf form.