You can go to settings on avast and in general tab go into exclusions there add a path to a folder with your trainers which you wish for avast to not scan.It is mildly amusing but I will say this its increasingly annoying now none of my trainers are working avast just decided to start flagging them today and me removing and saying they are fine doesn't do anything.
Be sure that the folder contains only files you know are safe and you are not going to put other potentially dangerous files there as it is effectively creating a blind spot for your antivirus.