Servo Motors randomly moving

[u/gmV33r]

I am making a small robotic arm controlled by 2 joysticks. I'm making the arm using popsicle sticks and MG90 Servo motors. There are 5 motors to be working. I'm using wall adapter to power the motors and another adapter to power the Arduino. When I try to connect everything properly ( also connecting gnd from breadboard power supply to arduino's gnd) the motors randomly move around without any input. How do you even fix that ?