I used "Nitro PDF Reader" (which is free) which u can download at download.cnet.com, not only did it let me edit and save my app, it also let me scan my signature and digitally place it on the pdf so I never had to print/scan the whole app 😀
ps. make sure you fill out the WHOLE app before you save it, cause i found that sometimes Nitro PDF Reader only lets you save once, every other time after just corrupts the file.