Macmini home theater system

mac mini (late 2014) on high sierra connected to sony bravia 75inch tv via HDMI.

Visio 5.1 (sound bar, sub and two speakers) connected to the TV via HDMi e arc.

If im watching the tv the sound is all good.

if i am watching a video / netflix through the mac mini the two small speakers dont work - just the sound bar and sub.

I have sniffed about for settings on both tv and mac and cant see anything obvious.

any ideas?

I would also like to increase the size of text / size of things on the mac so i can see tabs/text a little better, i have googled how to do that and the instructions dont line up with the options i get.

thanks