IDOLmain IP-7000 8000W Professional Digital Mixing Karaoke Amplifier

IDOL is not good product. I both 3 of them 1 EQ And 2 Mixing Amp I used 1year 2 year all gon

I have this IDOLmain IP-7000 8000W, but it has a problem: after I press the effect button on the remote control, I just turn on the microphone, it immediately howls, and howls (although not sing yet). What's the problem. Please show me how can I fix it? Thank you!