Data auto shift from one field to another field when i trying to upload a signature. and it's only with firefox.
Without anyone being able to go to that site or replicate the issue that will be hard to know what happened.
I can't see what is happening. Is it possible that you have enabled caret browsing? The f7 key toggles that on and off. Make sure you have NOT enabled Settings > General > Browsing > Always use the cursor keys to navigate within pages.