A quick fix for the glorious Delta aircraft made by TheFlyingDaggers47!
somehow the Auto-credit has failed so here's the link to the original aircraft: https://www.simpleplanes.com/a/RiI3NC/Delta

How I fixed the problem with pitching down was by simply removing some of the fuel that weighed down the aircraft from behind and instead adding fuel into other parts of the plane in the front to bring the centre of mass forward in front of the centre of lift. But what then happened was that the plane would stranegly pitch down even while pulling up, so to fix this I made the canards on the front of the aircraft also move by pitch to act like a second pair of elevators. I also had them rotated at an angle of 0.9 by default just so the plane doesn't keep pitching down when you're not pressing any controls. I hope you have fun with your freshly modified Delta!

PLEASE keep in my that this isn't mine so if you're planning on leaving an upvote, at least upvote the original build as well