Thank you for using my sheet :)) Different browsers and pdf viewers have different ways to show form fillable areas in pdfs. Some programs don't save the changes in your pdfs until you manually save it, and some don't let you edit form fillable sheets at all.
Character sheets should work on browsers like Edge and Chrome, I'd recommend them because they're the most accessible. But they won't save your sheets until you actively save or press ctrl + S, so remember to save whenever you edit your sheet or they will all go back to 0.
Hope this helps :)) thanks