What program are you creating the PDF from? If it is Word, then be aware that using the 'Save' option after making those changes will incorporate and store those changes, so that Word can undo them. To trim the file size, use the 'Save As' option to a new file name, which will delete the changes, and decrease the file size. This should help make a smaller PDF - assuming you are using the same compression (i.e. job settings) both times you make the PDF.