You most likely did this but in preferences as it is the same computer u play on all your accounts it stores info about each account i believe under family sharing. There is check boxes under all the steam names, MAKE SURE NONE ARE CHECKED. with it being checked it is not only telling valve you are doing family sharing but tags that account as an account that has to do with cheating. If you make that account on that day it usually checks it for you without you knowing. Just a tip and something i check everytime i go to hack.