operating multiple outputs from multiple inputs

Completely new to this so any help is appreciated.

I am wanting to operate 4 pwm outputs each tied to a separate potentiomter input from machine movement. I want to average the potentiometer signals individually then factor a manual potentiomter input to allow sensitivity adjustment by an operator to affect the pwm output.
Do I need to run 1 input output pair then move on to the next in the program, or does grouping matter?

I think I have the basics down to do 1 I/O pair but what about running all 4 at once?

There is really no such thing as "all at once"on a simple microcontroller.
The AVR has only one analogue converter, so conversions have to be sequential.
However, things happen very quickly, so things may appear to be simultaneous.