I believe if you want it to fly level, you should apply thrust more towards your airship's center of lift; the balloon icon; rather than that of your center of mass. Especially if your mass is below your lift.

That said if you lower your thrust down with your mass it should actually tip your airship's nose upwards?

YEAH FINALLY GOT IT TO work ty now just to figure out heli's

It might also have something to do with your cabin controls if you use W to go forward. If cabin controls are not disabled on your craft then W will also make it pitch down.

You can also try applying some Flaps, Wings, Tails to counter the thrusters.