You should probably go to an apple store, they can easily find out the problem for you, maybe for free, if not try and type what you wrote in you tube and maybe some suggestions come and tutorials on how you can fix this issue yourself via iTunes. Goodluck.

When I go and open YouTube app on my iPhone, the keyboard switches places to places, whenever I try and watch a video it freezes and it takes a lot of time, why?

Also, when ever I log on facebook on my iPhone, it doesn't update very quickly and its so slow when you want to read an article, help please ?

Like when I upgraded my iPhone 5 to IOS8 it became horrible, before my upgration it was slow but not like this

Any chance going back to way it was or fixing this problem ?

Thanks !