Question S4 (tottally working but..) boot up issue

My S4 is fully working but when I boot up my phone the touch buttons ( HOME and BACK) doesn't work sometimes so I need to restar my phone like 1-3 times to get these buttons working.... and second issue is that when I boot up my S4 I can't see the SGalaxy s4 logo ( The very first logo at the very begining of the boot up) I used to see that logo but now it's just gone..