You train older dogs the same way you treat puppies. You watch them ALL the time they are in the house and not in their crate. Keep them crated unless you are asleep or not at home. ALL other times you watch them and the instant that start to squat, you interrupt them and take them outside. You go out with them and when they do their business, praise and treat them. Never scold them or fuss in any way if they go inside. The only reason they are going inside is because they haven't yet been taught that it's wrong. If they do get away with it and you don't notice until its too late, its not their fault, its your fault for not watching closely enough.