Is there anything i should do to the check valve that is not being used at the moment?
if its not leaking gas, no.
im not exactly sure what you are looking for here... just close the ball valve on any of the connections that arent in use on the manifold. if you have ball or pin lock fittings on the lines, you dont even have to do that as they are self-sealing.
check valves arent adjustable (the check valve is inside the ball valve on most common manifolds), perhapse you are confusing the two...?