2006 Honda civic power streering

my son have a 2006 Honda civic i think its a 1.8 The power steering pulley screws keep working them selves out of the bracket that holds on the pulley ‘the first time this happened the bottom screw broke causing the belt to come off …now the top one has broken off causing the same problem . but I’m not sure if this is why because hes had this car for years and never a problem like this , can this be that the screws were the wrong size from the start even though they seem to fit. or could this be a tensioner problem.