Audio setting to "turn on" subs
 

The amp powers on but there's no response from the subs. Verified all the connections, ground and the connections to the head unit. Even changed the amp but same issue. This isn't a blown sub because this was an issue a few years back too which I fixed somehow by going through the settings in the head unit.

Would anyone have an idea what to change? It is a 2015 FRS with stock HU. I have switched between tC, FRS and xB and also hear, feel etc.

I know there isn't a "turn on sub" setting but an old thread mentioned something about "playing with settings".

Thank you