Fillable form from PC to iPad

Hi, I have downloaded some fillable PDF forms and works fine on PC, fill, edit and save etc..  I also saved them in Dropbox. Yet when I access them from iPad's Reader, the fillable field are frozen with all the info i typed in.  I tried to unlock that from the PC but i wasn't able to. 

However, if I export to Fill and Sign App, the info I typed in with PC are gone, a blank form with preexiting text will show, and I am able to fill in the form.  It will be really helpful if i can edit the PC info I typed in the IPad.

Thanks for the help

regards

chenyu