Do you unlock the device, then make a call and unable to access settings?
Or, you answer a call and cannot access settings?
The latter is normal.
The former would be a glitch.
Reboot yet?
example, I initiate a call, then attempt to access blue tooth or settings. the top of the page is phone call, green bar. I can access settings sometimes by swipe down from the top if If on the right side. its glitchy