motors not spinning toogether

Hi. I'm a beginner and this is my first activity in this forum. And this is my first ever RC build. I made a quadcopter using: APM 2.8 flight controller, 10x4.5 props, 1400KV BLDC, simonK 30 amps ESC, ublox neo 7m GPS with compass. And the radio system is flysky ct6b. Everything probably an...