how to change mac address with terminal emulator

From the main, fresh screen, I type 'su' (as in super user), Terminal gives a 'not found' error message I then tried just typing the second command, 'IP link show', and yea, same 'not found' message I tired starting from a fresh screen and skipping 'su', just starting with 'IP link show', same thing, not found (I even tried 'IP link' and got the same not found error). I'm reading that there is also a method using Terminal Emulator for Android and Busybox, I have never used the latter because nothing I type into Terminal works. When I go into Android settings and navigate to where it shows you what is going on with the root setting, it is not enabled and I am unable to slide it to the on position (I guess I am talking about 'rooting' the device - I get an error message when I try to do this anyway). I'm looking this up online, how to spoof a MAC address, but the method's I'm finding are not working.

I want to use this box in my shop and have the same MAC address on multiple devices. I bought the box a month or three ago, the software version is 6.0.1, not sure if that can be part of the problem (or, if so, how to update it).

How to change mac address with terminal emulator