Turn off all of your other events for setting the angles of you lazer and projectileimpulsion.
Add the events and variables in from my post.
Replace the "turret" in event #3 in my events with "lazer" from yours. (event #13)
Now edit the event Projectileimpulsion - set angle to AngleDiffViseurPerso and instead set angle to lazer.angle. (event #18)
Now the angle of the turret and any spawned projectiles will be set towards the mouse position if the mouse is moving. If the mouse is not moving they will be set to the last angle.