[Help] [Router QoS]: can someone tell me how to limit internet access for users on router Huawei hg531s1 v1?

I have limited internet quota, and some users used it up in the first 10 days of the month, so i need to limit the speed and quota (if possible) for every single user... We are nearly 10 users, the router works mainly for wifi, there is only one cable plugged to the router to connect a switch to it, about 5 users use the switch by wifi only too (those 5 who used up the quota), so i read about QoS and MAC addresses, but I couldn’t do all the options well, can someone explain it in details?