issues with 7.1 surround and Xumo box

In trying to figure out getting some TV options at a price I can handle, Ive tried many options through XFinity....got sent a Xumo box instead of the Flex box which I still have.....I dont recall tho cant be sure as its not active now having the issue I am now for sure which is whatever app or stream be itt Xumo, Xfinity, Youtube even, my read speakers imply dont work.  Ive tried resetting connections etc and changed nothing on my end though I believe the issue began when I got sent the Xumo box.
I am sure that the same video palyed thru youtube from y samsung TV plays thru the rear speakers while it does not thru Xfinity box....which is a bummer and unless fixed means i do not want to pay for this and shouldnt.  The rea bass box works but nothing comes thru the speakers and again yes ive tried everything I can think of including various things to watch and as I said the true clue to me either some setting Idk to change or the box itself are why my rear speakers dont work... any which way i want the sound fixed or am cutting off the TV streaming and giving up after months of trying. various ways essentially to pay xfinity for reasonable options.. thanks