Look for this under near the gas pedal. Turn all the knobs to left and play around with this part. It loosens and tightens the cable. Try turning to knobs all the way to the right if turning the knobs to the left doesn't work.
The terminals are kinda funky and I want to replace them with these:
Fastronix Military Spec Battery... https://www.amazon.com/dp/B00X36RILW/?tag=m20b7-20.
But, I think the copper lugs that came in the package are a bit too big for the smaller wires.