ios backbutton at top of the screen In many apps like safari or youtube the backbutton is at the top of the screen. That makes it basically impossible to use my ipad pro 9.7 comfortably in bed, I would have to sit up and use both hands to access the back button. Is there any way to get a back button at the bottom of the screen?
I'm not aware of any way of doing this within iOS proper (although there may be a way to implement such a feature on a jailbroken device).

However, you could just double tap the home button to then select the previous app from the screen. 

Also, using your iPad in landscape (I.e. Sideways) may help with accessing the default 'back' button.