Big finishing issue

Ok I love this game, but theres one problem. Im at safer sephiroth right now and theres multiple issues right now. 1, I have a 5s and should be able to operate correctly. 2.I remember him having like 70,000 hp not like 999,999 or something, he wont die!!!3,sometimes when Im doing good, the game just closes out on me!!! I want these issues to be fixed, but until then dont play too much and get to the final boss. Thank you

Gohanks777 games about FINAL FANTASY VII